Foretravel Motorhome Forums => Foretravel Tech Talk => Topic started by: cucotx on February 27, 2021, 12:41:15 pm
Title: Tires - Michelin 2004 U320 - Steer vs. Drive tires - 275/80R22.5 vs. 295/80R22.5
Post by: cucotx on February 27, 2021, 12:41:15 pm
Hi All,
I may be buying a 2004 U320 soon. I'm planning to replace the aging tires on that coach.
For that 40' with Tag Axle and 8 tires, I was thinking of using 295/75R22.5. But, unfortunately, FMCA does not list the 295/75R22.5 in the list of tires on sale. So, I'm looking for advice on what my options are for the coach.
1 - FMCA does offer various 275/80R22.5 LRH and some of the 295/80R22.5 LRH.
2 - Is the 275/80R22.5 LRH tire undersized for any of the axles in the MH? I think FT eventually went to the 295/75R22.5. Here are the 275/80R22.5 LRH tires on sale from Michelin.
XLine Energy Z XZE 149 L X MultiEnergy Z
If I go with the 275, I wonder which one of the above would work best for the MH?
The MultiEnergy is also available as a "MultiEnergy D" for the drive axle but only in a LRG. I wonder if a "G" load rating is okay for the drive axles? Should I put "D" tires for the drive axles? Can the steer axle tire, e.g. MultiEnergy Z be used in the drive axles?
3 - Since the 295/75R22.5 are not available through FMCA, I wonder if I can use the 295/80R22.5 on the MH. Slightly taller than the 295/75R22.5.
Choosing a tire seems to be part art part science. Thanks in advance for the help with this.
:help:
Title: Re: Tires - Michelin 2004 U320 - Steer vs. Drive tires - 275/80R22.5 vs. 295/80R22.5
Post by: craneman on February 27, 2021, 01:00:45 pm
295/80/22.5 will rub when mounted on the front axle. Haven't seen any posts of them on the rear but probably a problem too.
Title: Re: Tires - Michelin 2004 U320 - Steer vs. Drive tires - 275/80R22.5 vs. 295/80R22.5
Post by: Roger & Susan in Home2 on February 27, 2021, 01:38:41 pm
I have all steer tires on our coach.
Title: Re: Tires - Michelin 2004 U320 - Steer vs. Drive tires - 275/80R22.5 vs. 295/80R22.5
Post by: cucotx on February 27, 2021, 01:52:59 pm
Roger,
Since the steering tires work in the drive and tag axles as well, why would Michelin be making tires specifically for the drive axles? The drive axle tires from Michelin that I got a quote on were more expensive than the same type "MultiEnergy" steering tires and at a lower "G" rating than the "H" rating of the same type of steering tires. Is the saving on diesel that much better with "D" tires on for drive and tag axles?
Title: Re: Tires - Michelin 2004 U320 - Steer vs. Drive tires - 275/80R22.5 vs. 295/80R22.5
Post by: Travelin' Man (RIP) on February 27, 2021, 02:09:26 pm
275/80R22.5 is the correct size tire for a '04.
The Michelin X Multi Energy Z (H) gives me the best ride because it requires 15lbs less pressure than all other tires of that size and load range to carry the same axle weight.
I don't know about the tag axle but for the other two axles I would get all the same 275/80R22.5 steer tires in the correct load range.
Title: Re: Tires - Michelin 2004 U320 - Steer vs. Drive tires - 275/80R22.5 vs. 295/80R22.5
Post by: wolfe10 on February 27, 2021, 02:19:29 pm
Steer tires on all wheel positions is the recommended tire.
Traction tires are more for trucks operating in slick/off road conditions. Not recommended for a motorhome.
Title: Re: Tires - Michelin 2004 U320 - Steer vs. Drive tires - 275/80R22.5 vs. 295/80R22.5
Post by: cucotx on February 27, 2021, 02:49:21 pm
Wow, the collective experience of members in this forum is awesome. The knowledge shared by others and provided via this forum sure makes it easier when deciding that it is okay to buy an older Foretravel motorhome. ^.^d
Now I need to decide which Michelin tire to purchase, or if I should go with Toyo, Goodyear or other. I can probably save some money by going with Toyo, but Michelin do show up in many motorhomes. Nothing wrong with sticking with what we know, I guess.
Title: Re: Tires - Michelin 2004 U320 - Steer vs. Drive tires - 275/80R22.5 vs. 295/80R22.5
Post by: Roger & Susan in Home2 on February 27, 2021, 02:56:00 pm
You will want to get H load rated tires. They have a higher weight capacity than the G load rating at the same air pressure, a higher maximum load capacity and have a stiffer side wall which makes then feel more stable especially in cross winds.
For the same axle load you can run H rated tires at a lower pressure. Your front axle fully loaded will exceed the capacity of a G rated tires.
Best practice is to have the coach loaded as it would normally be when traveling with empty waste tanks, full fresh water tank, full fuel tank and weigh each corner and then set set the tire pressured for each axle based on the higher corner weight on each axle according to the tire load/psi charts. Most go up to the next higher level for some flexibility in weights. Our coach seemed to gain weight for a few years while we figured out what to bring and then lose some as we figured out what we didn't need. It is a bit different with a tag as that carries part of the rear load. Someone with a tag can say how to set the rear axle and tag axle pressures.
Title: Re: Tires - Michelin 2004 U320 - Steer vs. Drive tires - 275/80R22.5 vs. 295/80R22.5
Post by: dsd on February 27, 2021, 03:35:24 pm
Would be preferred to get the coach weighed and know that H tires meet your needs. Not all H carry the same rating. I was looking for function over form and the Toyo M 177 H fit my needs well. All steer tires. Michelin probably will be the best accepted tires by owners. Mine may be a little noisier, but I'll never know for sure. Very happy with my purchase. Purchased thru a COOP in Arkansas for $2400 for six. Cheaper than what I could find online. 100% happy with them. Currently would repeat in the future. I have 6500 miles so still new to me. Side note. 100% recommend truck size tire balance beads and personally am very happy with my TST TPMS. Better than a spare IMO. Wouldn't operate without. 👍👍 Scott
Title: Re: Tires - Michelin 2004 U320 - Steer vs. Drive tires - 275/80R22.5 vs. 295/80R22.5
Post by: Rudy on February 27, 2021, 03:49:02 pm
Peter, I sent you a PM. Please call
Title: Re: Tires - Michelin 2004 U320 - Steer vs. Drive tires - 275/80R22.5 vs. 295/80R22.5
Post by: Pierce & Gaylie Stewart on February 28, 2021, 12:26:58 pm
295/75R22.5 would be my choice in G or H depending on your weight. Lower profile means more rubber on the ground. Lots of motorhomes with Michelin tires but they also have a reputation for zipper sidewalls and poor casing life. Lots of good tires on the market from all over the world. Don't think country of manufacture makes the slightest difference.
Good read here on tire brand rating: Top 10 Best Commercial Truck Tire Brands. | This is just the beginning of... (https://mdcsiteuno.wordpress.com/2012/10/06/top-10-best-commercial-truck-tire-brands/)
After a flat, I put a new Firestone (Bridgestone) on and many years later, the sidewalls do not have even a trace of a crack. Same can't be said for the other tires. I'm about to replace all except the Firestone. Bridgestone recommends a maximum of 15 years for their casings used in recapping.
Then you have to decide on regional or line/long haul tires.
Pierce
Title: Re: Tires - Michelin 2004 U320 - Steer vs. Drive tires - 275/80R22.5 vs. 295/80R22.5
Post by: cucotx on February 28, 2021, 08:37:19 pm
So Michelin does not make a 295/75R22.5. Their "H" load rated 275/80R22.5 is maxed at 7160 lbs. The GAWR for the 2004 U320 is 14320 lbs. So the "H" rating just meets the GAWR. I would prefer a better load rating. Some more room for off-balanced weighing on the front axle.
I did some research into the Bridgestone, but their "H" rated that I saw, the R268 Ecopia 149L is also 7160 lbs. Pierce, is there another Bridgestone that I should consider for better load rating?
I haven't had a chance to look at any other tires.
I do agree that I think there may be a better and cheaper tire for motorhomes than the Michelin. I won't select the Michelin until I finish this research.
Title: Re: Tires - Michelin 2004 U320 - Steer vs. Drive tires - 275/80R22.5 vs. 295/80R22.5
Post by: AC7880 on February 28, 2021, 11:48:26 pm
Full timing with everything we own on board. 2003 40' U320 dual slide, tag axle. Continental 275/80R22.5 H rated tires.
Oregon weigh station (closed) 6/28/2020 Fuel approx. 150 gal, water only approx. 35 gal, black/grey empty (add 900 lbs for full water/fuel)
and Oregon weigh station (closed) 7/8/2020 Fuel approx. 130 gal, water 85 gal, grey/black empty
Steer 12,850 6/28, 12,850 7/8. P.O 12,175 (equal 105 psi or 110 psi margin for tires on coach) (P.O = previous owner weight reading)
Drive 16,100 6/28. 18050 7/8. (difference likely due to position on scale) P.O 16,600 (equal 75 psi) (or 80-85 psi margin)
***** WINTER - NOW SET AT 114/85/80 PSI AT 50 DEGREES - MARGIN FOR COLDER DAYS *****
275/80R22.5 H rated tires.
Title: Re: Tires - Michelin 2004 U320 - Steer vs. Drive tires - 275/80R22.5 vs. 295/80R22.5
Post by: Pierce & Gaylie Stewart on February 28, 2021, 11:50:08 pm
Here is the standard load rating chart for tires. The 295/75R22.5 ratings are down a bit from the top on the page. https://irp-cdn.multiscreensite.com/400c5684/files/uploaded/Load,%20Inflation%20table.pdf
Anytime you are going to put 120 psi cold in a tire that is H rated, the ride may be a bit firmer than expected.
Lots of good tires on the market from lots of different manufacturers. The tires that cost the most will usually advertise the most so cost is not a reliable indicator of the quality of the tire.
Since RVs don't rack up a lot of miles compared to big rigs, the longevity of the casing should be one of the top priorities. In other words, no cracks in the sidewall should develop.
I like tires with a fairly firm sidewall for several reasons. The are less prone to damage from curbs, etc and they don't allow the coach to move as much in crosswinds and uneven pavement. For coaches with a high seating position like a U280/U300, a driver who can't resist constantly moving the steering wheel will make for a unpleasant ride for passengers.
Usually, the heavier the tire, the better the quality.
I can't understand someone who buys a tire with lots of tread depth and then goes and have some shaved off.
Pierce
Title: Re: Tires - Michelin 2004 U320 - Steer vs. Drive tires - 275/80R22.5 vs. 295/80R22.5
Post by: cucotx on March 01, 2021, 04:46:35 pm
So what I just realized is that the maximum load rating found with some "H" tires is going to be plenty for the coach. The GAWR for the front axle of the 2004 U320 is 14200 lbs. For my plans, I should never get close to that weight. So two tires that each have 7160 lbs rating is fine. I think the CCC of the coach is over 6000 lbs. As per Dan's entry above, his steer axle load, while fully loaded for fulltiming, is under 12900 lbs. I don't plan to add much more than that to my coach, so that should keep me under the ratings of the "H" tires. My current plan is to add solar and lithium batteries to the coach. From the pictures that I have of the roof of the coach, most of those solar panels can only go towards the back section of the roof. That's weight for the rear axle to handle. The U320 already has a lot of other stuff mounted on the front section of the roof.
In addition to the solar panels, I plan to remove the 3 8D batteries in the coach and replace them with Lithium 8D batteries from Battleborn. Possibly, their new Lithium BB8D 8D sized 270 AH batteries. Those batteries are 80 lbs instead of the 8D batteries in the motorhome at over 140 lbs? So that will save some weight. If there is more room, I my add more Lithium batteries in other places in the coach. The lithium upgrade would definitely be nice for a trip to a Harvest Host or other boondocking scene. Three of the BB8D would provide about 800 AH of fully useable power at 12 V (9.6 KW-Hr). That is definitely nice.
Pierce, I liked what you said about selecting the tire with the best casing and stiffest sidewall. I'll look at those specs for the Michelin, Toyo, Bridgestone and others.
I also like the idea of going with the 295/75R22.5 instead of the 275/80R22.5. The wider tire would maximize how much rubber is on the road. But, I need to find an "H" rated 295 with a rating close to that of a 275/80R22.5 at 7160 lbs.
Title: Re: Tires - Michelin 2004 U320 - Steer vs. Drive tires - 275/80R22.5 vs. 295/80R22.5
Post by: valento on March 01, 2021, 05:41:36 pm
I have a 2004 U320 3820 and put Michelin 295/80R22.5 XZA2 ENERGY 152M LRH on my coach. No problems with rubbing on the steer axle. Maybe I just got lucky ;) . I spoke with Tyle Fore at FOT and he told me it should not be a problem and it has not been.
Title: Re: Tires - Michelin 2004 U320 - Steer vs. Drive tires - 275/80R22.5 vs. 295/80R22.5
Post by: cucotx on March 01, 2021, 05:51:18 pm
Oscar and Janet, that is great news. If I can, I would rather have the 295/80R22.5 as well. The typical 295/80R22.5 "H" tire has about a 7400lb rating at 115 psi. With Dan's reported "typical" weight on the front axle of about 12900 lbs, that means I could lower the running pressure on those tires by a lot. That is good, right? BTW, I'm learning more about tires than I really wanted to know.
The 2004 U320 that I'm looking at is a 4020. I may have to give FOT a call.
Did you get a chance to change the drive and tag tires with the same tire as well?
Title: Re: Tires - Michelin 2004 U320 - Steer vs. Drive tires - 275/80R22.5 vs. 295/80R22.5
Post by: valento on March 01, 2021, 05:56:12 pm
"In addition to the solar panels, I plan to remove the 3 8D batteries in the coach and replace them with Lithium 8D batteries from Battleborn. Possibly, their new Lithium BB8D 8D sized 270 AH batteries. "
Take a look at LifeBlue Model LB12300-HC lithium batteries. I have 8 of them in my coach and 3320w of solar panels on my roof. I have been off grid full timing for about 16 months with them and have only used 7 cycles out of the 3000 guaranteed.
Title: Re: Tires - Michelin 2004 U320 - Steer vs. Drive tires - 275/80R22.5 vs. 295/80R22.5
Post by: valento on March 01, 2021, 05:57:17 pm
Oscar and Janet, that is great news. If I can, I would rather have the 295/80R22.5 as well. The 2004 U320 that I'm looking at is a 4020. I may have to give FOT a call.
Did you get a chance to change the drive and tag tires with the same tire as well?
Did all 8 tires - ouch $$$$
Title: Re: Tires - Michelin 2004 U320 - Steer vs. Drive tires - 275/80R22.5 vs. 295/80R22.5
Post by: Pierce & Gaylie Stewart on March 01, 2021, 05:57:31 pm
So what I just realized is that the maximum load rating found with some "H" tires is going to be plenty for the coach. The GAWR for the front axle of the 2004 U320 is 14200 lbs. For my plans, I should never get close to that weight. So two tires that each have 7160 lbs rating is fine. I think the CCC of the coach is over 6000 lbs. As per Dan's entry above, his steer axle, while fulltiming, is under 12900 lbs. I don't plan to add much more than that to my coach, so that should keep me under the ratings of the "H" tires. My current plans is to add solar and lithium batteries to the coach. From the pictures that I have of the roof of the coach, most of those solar panels can only go towards the back section of the roof. That's weight for the rear axle to handle. The U320 already has a lot of other stuff mounted on the front section of the roof.
In addition to the solar panels, I plan to remove the 3 8D batteries in the coach and replace them with Lithium 8D batteries from Battleborn. Possibly, their new Lithium BB8D 8D sized 270 AH batteries. Those batteries are 80 lbs instead of the 8D batteries in the motorhome at over 140 lbs? So that will save some weight. If there is more room, I my add more Lithium batteries in other places in the coach. The lithium upgrade would definitely be nice for a trip to a Harvest Host or other boondocking scene. Three of the BB8D would provide about 800 AH at 12 V. That is definitely nice. Pierce, I liked what you said about selecting the tire with the best casing and stiffest sidewall. I'll look at those specs for the Michelin, Toyo, Bridgestone and others. I also like the idea of going with the 295/75R22.5 instead of the 275/80R22.5. The wider tire would maximize how much rubber is on the road.
Peter,
There are always compromises when it comes to tires, ride, sidewall, pressure, casing durability, etc.
You have probably noticed that through the years, lower profile (aspect ratio) tires have become the way to go with each year finding lower and lower profile tires on street vehicle. The bigger footprint will stop, corner, and overall, handle better. The down side here is there is less distance between the rim/wheel and the ground so the tire will have less distance to flex. Suspensions have changed a lot with progressive shock absorbers and spring rates making the ride comfortable even with the short wheel to ground distance.
With an RV, there is going to be a bit of a difference between a 295/75 and a 275/80 but not much as far as ride goes. The additional width will stop better, etc. but the actual differences will vary between manufactures. The 295 may polish the bottom mount on the air bags on certain turns with the coach in a certain attitude but there is no harm done.
When you replace your airbags, most of the time you put on Firestone or Conti bags. Since Firestone is owned by Bridgestone, that's the parent company. With Conti, it's Continental Tire and Rubber, also the maker of excellent tires for big coaches or cars as well as other quality products. Even the Chinese are outsourcing some of their tires to other countries, so the country of origin is not that important.
The bottom line is that everyone wants a tire with a low failure rate, long casing life with minimum sidewall cracking as the tire ages, a good ride, good handling, a round tire that also takes the minimum amount of weights to balance, low noise and a tire that does well in all weather conditions.
Maxing out the pressure on an H rated tire may give a firmer ride than you like. We run our G load rated tires at 110 psi all the way around and find the ride is just fine. Others don't.
To get an idea of which tire does what, it pays to call around to large volume tire dealers. Here is an example of a tire shop I have called for information and pricing. I used 295/75R22.5, domestic and imported, steer and all position for the list here: Discount Import Steer 295/75R22.5 Tires for Sale, USTireOutlet.com (https://www.ustireoutlet.com/import-steer-295-75r22-5/)
Pierce
Title: Re: Tires - Michelin 2004 U320 - Steer vs. Drive tires - 275/80R22.5 vs. 295/80R22.5
Post by: cucotx on March 01, 2021, 06:27:38 pm
"Take a look at LifeBlue Model LB12300-HC lithium batteries. I have 8 of them in my coach and 3320w of solar panels on my roof."
I'll check the LifeBlue batteries. How did you manage to mount 3320w of solar on the FT?
Title: Re: Tires - Michelin 2004 U320 - Steer vs. Drive tires - 275/80R22.5 vs. 295/80R22.5
Post by: valento on March 01, 2021, 06:33:11 pm
"How did you manage to mount 3320w of solar on the FT?"
I had AMSolar do the entire install for I do not have the tools or expertise. You can PM me for more info.
Title: Re: Tires - Michelin 2004 U320 - Steer vs. Drive tires - 275/80R22.5 vs. 295/80R22.5
Post by: AC7880 on March 01, 2021, 06:53:07 pm
So what I just realized is that the maximum load rating found with some "H" tires is going to be plenty for the coach. The GAWR for the front axle of the 2004 U320 is 14200 lbs. For my plans, I should never get close to that weight. So two tires that each have 7160 lbs rating is fine. I think the CCC of the coach is over 6000 lbs. As per Dan's entry above, his steer axle load, while fully loaded for fulltiming, is under 12900 lbs. I don't plan to add much more than that to my coach, so that should keep me under the ratings of the "H" tires. My current plans is to add solar and lithium batteries to the coach. From the pictures that I have of the roof of the coach, most of those solar panels can only go towards the back section of the roof. That's weight for the rear axle to handle. The U320 already has a lot of other stuff mounted on the front section of the roof.
In addition to the solar panels, I plan to remove the 3 8D batteries in the coach and replace them with Lithium 8D batteries from Battleborn. Possibly, their new Lithium BB8D 8D sized 270 AH batteries. Those batteries are 80 lbs instead of the 8D batteries in the motorhome at over 140 lbs? So that will save some weight. If there is more room, I my add more Lithium batteries in other places in the coach. The lithium upgrade would definitely be nice for a trip to a Harvest Host or other boondocking scene. Three of the BB8D would provide about 800 AH of fully useable power at 12 V (9.6 KW-Hr). That is definitely nice.
Pierce, I liked what you said about selecting the tire with the best casing and stiffest sidewall. I'll look at those specs for the Michelin, Toyo, Bridgestone and others.
I also like the idea of going with the 295/75R22.5 instead of the 275/80R22.5. The wider tire would maximize how much rubber is on the road. But, I need to find an "H" rated 295 with a rating close to that of a 275/80R22.5 at 7160 lbs.
I have 1440 watts solar on my roof. That is included in the weights I provided above. One more panel was added since the pic - at passenger side front of coach.
Title: Re: Tires - Michelin 2004 U320 - Steer vs. Drive tires - 275/80R22.5 vs. 295/80R22.5
Post by: cucotx on March 16, 2021, 06:26:57 pm
After much boring research into truck/bus tires, I have decided to go with 8 of the Michelin X COACH H LZ LRH, sized 295/80R22.5.
Some of you are probably saying, overkill :o . Even the salesman for the tires told me so. He was recommending something cheaper. But, it's what I usually do. I go overboard. Safety first. :facepalm:
BTW, I do have an email out to FOT to confirm that I can install the 295/80 on the 2004 U320 4020 before I order them.
I chose that tire for three reasons:
1 - I do like the idea of the wider 295 thread.
2 - The Michelin Infini-Coil technology for better contact with the road and its stronger casing.
3 - A load rating of 8270 lbs at 123 psi. This means that for the U320, I may be able to run the steering tires at 90 to 95 psi.
I also plan to install the Centramatic wheel balancing system. But I still need to read up on that. For now, I'm assuming that all 8 tires would need the Centramatics on it?
Title: Re: Tires - Michelin 2004 U320 - Steer vs. Drive tires - 275/80R22.5 vs. 295/80R22.5
Post by: Rudy on March 16, 2021, 06:42:49 pm
I may be wrong, but those larger diameter tires may rub your mounting plates for your air springs. My 295 75R 22.5 tires just missed when turned to either side. Let us know.
Plus, hope you like the CentraMatics as much as I do on all 8 tires
Title: Re: Tires - Michelin 2004 U320 - Steer vs. Drive tires - 275/80R22.5 vs. 295/80R22.5
Post by: Pierce & Gaylie Stewart on March 16, 2021, 06:46:07 pm
After much boring research into truck/bus tires, I have decided to go with 8 of the Michelin X COACH H LZ LRH, sized 295/80R22.5. BTW, I do have an email out to FOT to confirm that I can install the 295/80 on the 2004 U320 4020 before I order them.
[/quote] Make sure FOT gives the go ahead for clearance to the airbags, etc. The new tire will be about 1.1 inches taller so interference is possible. The taller tires will also cut the tire to fender well distance in the back. 295/80-R22.5 vs 295/75-R22.5 Tire Comparison - Tire Size Calculator | Tacoma... (https://www.tacomaworld.com/tirecalc?tires=295-80r22.5-295-75r22.5)
Pierce
Title: Re: Tires - Michelin 2004 U320 - Steer vs. Drive tires - 275/80R22.5 vs. 295/80R22.5
Post by: Chuck & Jeannie on March 16, 2021, 06:48:11 pm
I also plan to install the Centramatic wheel balancing system. For now, I'm assuming that all 8 tires would need the Centramatics on it?
On a motorhome with dual rear drive wheels, the Centramatic goes between the rear wheels on each side, so you need a total of 4 Centramatics to do all 4 corners of the coach. See the installation videos:
The new tire will be about 1.1 inches taller so interference is possible.
Hi Pierce,
I think the concern for the clearance to anything around the tire would be the sidewall height difference at 0.58" when comparing the 295/75 to the 295/80. I'm thinking the other 0.58" size change with the 295/80 that is below the axle just lifts the MH off the road. So I think I just need 0.58" clearance.
When compared to the original 275/80 from the factory, the 295/80 would have an additional sidewall height of about 0.63" that would need clearing.
Title: Re: Tires - Michelin 2004 U320 - Steer vs. Drive tires - 275/80R22.5 vs. 295/80R22.5
Post by: cucotx on March 16, 2021, 09:08:16 pm
Chuck and Jeannie,
I'm also assuming that the tag axle would need two centramatics for those tires as well?
Title: Re: Tires - Michelin 2004 U320 - Steer vs. Drive tires - 275/80R22.5 vs. 295/80R22.5
Post by: Pierce & Gaylie Stewart on March 16, 2021, 09:25:11 pm
I think the concern for the clearance to anything around the tire would be the sidewall height difference at 0.58". I'm thinking the other 0.58" size change with the 295/80 that is below the axle just lifts the MH off the road. So I think I just need 0.58" clearance.
You are correct in that it will come just over a half inch closer to the top of the wheel well and the same in the front. But 0.58 may touch the bottom of the air bag plate a lot more than our 295/70 where the contact is only in certain turns and attitudes. FOT will know exactly how much.
Pierce
Title: Re: Tires - Michelin 2004 U320 - Steer vs. Drive tires - 275/80R22.5 vs. 295/80R22.5
Post by: Chuck & Jeannie on March 16, 2021, 09:31:52 pm
Richard, On your U320, do you use 600-630 on both steer and tag axles and the 600-640 Centramatic on the drive axle?
Title: Re: Tires - Michelin 2004 U320 - Steer vs. Drive tires - 275/80R22.5 vs. 295/80R22.5
Post by: cucotx on March 17, 2021, 04:16:41 pm
The response for my email to FOT is as follows:
"The 2004 U320 was equipped with a 275-80R/22.5 tire and we recommend replacing it with the same size. "
The above from the "Director of Warranty and Technical Support".
They didn't say the 295/80 won't fit. But, it is the correct response that I would expect from any manufacturer to a question like this via email. I wasn't hopeful that they would confirm that it would fit, even if it does. All their warranty work and design is based on the 275/80. I suppose a concern from a manufacturer is that people will use beefier tires and then end up overloading the axle, frame or other components with weight in the coach above the GAWR. I think what I'll do is wait until I get the RV and take clearance measurements to see if I can fit the 295/80.
Valento got a different response from FOT to the same question for his 2004 U320 3820 and the tires had clearance. So, I would think it should fit a 2004 U320 4020.
Now, from a design point of view, other than the clearance issues, I wonder if the weight difference between the 295/80 tire and the 275/80 tire would be large enough to make a difference to the 22.5 wheel and/or axle. The 295/80 should not be more than about 20 lbs heavier than the 275/80. So, I would think that should not be of concern to the axle or wheel. Does anyone know?
Title: Re: Tires - Michelin 2004 U320 - Steer vs. Drive tires - 275/80R22.5 vs. 295/80R22.5
Post by: oldguy on March 17, 2021, 04:50:12 pm
I believe 295-75R/22.5 is the same dimensions as the 275.80R/22.5
Title: Re: Tires - Michelin 2004 U320 - Steer vs. Drive tires - 275/80R22.5 vs. 295/80R22.5
Post by: rbark on March 17, 2021, 04:55:32 pm
Peter, as to the size of my centermatics, I have no idea. Although I have had my tires changed, I wasn't around till they were done. Not sure but I think the company's web site will have that information.
Title: Re: Tires - Michelin 2004 U320 - Steer vs. Drive tires - 275/80R22.5 vs. 295/80R22.5
Post by: cucotx on March 17, 2021, 04:57:26 pm
I believe 295-75R/22.5 is the same dimensions as the 275.80R/22.5
They're almost the same size, but Michelin doesn't sell the "X Coach" in the 295/75 size.
Title: Re: Tires - Michelin 2004 U320 - Steer vs. Drive tires - 275/80R22.5 vs. 295/80R22.5
Post by: Pierce & Gaylie Stewart on March 17, 2021, 05:08:43 pm
I believe 295-75R/22.5 is the same dimensions as the 275.80R/22.5
Just about exactly the same diameter but the aspect ratio on the 295/75 does mean the 7.3% wider tire polishes the bottom plate on the air bag. At least it does on ours. So what does that mean on a taller 295/80?
No real problem on the back.
Pierce
Title: Re: Tires - Michelin 2004 U320 - Steer vs. Drive tires - 275/80R22.5 vs. 295/80R22.5
Post by: cucotx on March 17, 2021, 05:15:25 pm
Just about exactly the same diameter but the aspect ratio on the 295/75 does mean the 7.3% wider tire polishes the bottom plate on the air bag. At least it does on ours. So what does that mean on a taller 295/80?
No real problem on the back.
Pierce
But Pierce, the part I don't understand is why does it clear on the 2004 3820 U320? Could it be that the spacing for your U300 for the wheel is different for that of the U320.
Title: Re: Tires - Michelin 2004 U320 - Steer vs. Drive tires - 275/80R22.5 vs. 295/80R22.5
Post by: Pierce & Gaylie Stewart on March 17, 2021, 05:51:53 pm
But Pierce, the part I don't understand is why does it clear on the 2004 3820 U320? Could it be that the spacing for your U300 for the wheel is different for that of the U320.
You didn't give the tire size on the U320. Are you saying the 295/80R22.5 clears on the U320? If so, you are probably home free.
Pierce
Title: Re: Tires - Michelin 2004 U320 - Steer vs. Drive tires - 275/80R22.5 vs. 295/80R22.5
Post by: cucotx on March 17, 2021, 06:00:06 pm
Valento installed the 295/80 on his U320 3820. I wonder how much clearance he has with the bottom of the mounting to the airbags?
Title: Re: Tires - Michelin 2004 U320 - Steer vs. Drive tires - 275/80R22.5 vs. 295/80R22.5
Post by: wolfe10 on March 17, 2021, 06:02:07 pm
May partially depend on what CUT ANGLES are set in the Sheppard steering box.
Title: Re: Tires - Michelin 2004 U320 - Steer vs. Drive tires - 275/80R22.5 vs. 295/80R22.5
Post by: cucotx on March 17, 2021, 06:07:55 pm
May partially depend on what CUT ANGLES are set in the Sheppard steering box.
Yea. It would be nice if we had others in the forum that have tried the bigger tires in the U320 and could comment on this.
Brett, do you think an extra 20 lbs with the bigger tire would be an issue with the U320 wheel, axle or other component? Other than clearance, that would be the remaining concern.
Title: Re: Tires - Michelin 2004 U320 - Steer vs. Drive tires - 275/80R22.5 vs. 295/80R22.5
Post by: wolfe10 on March 17, 2021, 06:10:47 pm
Sorry, no first experience.
Title: Re: Tires - Michelin 2004 U320 - Steer vs. Drive tires - 275/80R22.5 vs. 295/80R22.5
Post by: Pierce & Gaylie Stewart on March 17, 2021, 06:12:58 pm
Yea. It would be nice if we had others in the forum that have tried the bigger tires in the U320 and could comment on this.
Brett, do you think an extra 20 lbs with the bigger tire would be an issue with the U320 wheel, axle or other component? Other than clearance, that would be the remaining concern.
Same width, just taller so your revs per mile would be less. Not a bad thing. If I were sure it cleared the front bags, I would probably mount the taller size.
Pierce
Title: Re: Tires - Michelin 2004 U320 - Steer vs. Drive tires - 275/80R22.5 vs. 295/80R22.5
Post by: oldguy on March 17, 2021, 06:41:45 pm
I believe the 295-75R/ 22.5 is the same dimensions as the 275-80R/22.5 or very close.
Title: Re: Tires - Michelin 2004 U320 - Steer vs. Drive tires - 275/80R22.5 vs. 295/80R22.5
Post by: wolfe10 on March 17, 2021, 06:44:39 pm
I believe the 295-75R/ 22.5 is the same dimensions as the 275-80R/22.5 or very close.
Correct.
But, 275/80 to 295/80 is different.
Title: Re: Tires - Michelin 2004 U320 - Steer vs. Drive tires - 275/80R22.5 vs. 295/80R22.5
Post by: Pierce & Gaylie Stewart on March 17, 2021, 07:17:34 pm
All anyone has to do is type in any two sizes 275/80-R22.5 vs 295/75-R22.5 Tire Comparison - Tire Size Calculator | Tacoma... (https://www.tacomaworld.com/tirecalc?tires=275-80r22.5-295-75r22.5) and you get the all the information including speedo error plus you can overlay the tires. It's a no brainer. Should end any arguments.
Title: Re: Tires - Michelin 2004 U320 - Steer vs. Drive tires - 275/80R22.5 vs. 295/80R22.5
Post by: Protech Racing on March 17, 2021, 09:09:29 pm
The larger, heavier tire will slow down the acceleration and cost a little fuel use.
Title: Re: Tires - Michelin 2004 U320 - Steer vs. Drive tires - 275/80R22.5 vs. 295/80R22.5
Post by: red tractor on March 17, 2021, 09:17:48 pm
I would measure how close the 275/80r 22.5 is to the lower plate in front while turning and then compare the diameter of the 2 sizes to make a comparison. On our 98 I took it to a tire place and he told me that he had put a larger tire on it. As I left the lot when I turned the wheels it rubbed real hard. Took it back the next day and he put on 295/75r22.5 tires and no rubbing but I don't know what size he had put on first.
Title: Re: Tires - Michelin 2004 U320 - Steer vs. Drive tires - 275/80R22.5 vs. 295/80R22.5
Post by: Pierce & Gaylie Stewart on March 17, 2021, 10:55:29 pm
Real world conditions are different than just turning the wheel and seeing if it touches or how close it comes. Ours is very close to touching in a static demonstration but when turning and loading the coach, especially on uneven ground, it does touch. Going forward, it just polishes the bottom plate. It could possible do more than that if the coach were in reverse. I'm thinking about backing into a campsite on gravel or dirt.
Pierce
Title: Re: Tires - Michelin 2004 U320 - Steer vs. Drive tires - 275/80R22.5 vs. 295/80R22.5
Post by: FourTravelers on March 18, 2021, 06:30:19 am
Pierce brings up a good point....... so if the larger tires aren't really needed.....?..... I would seriously consider staying with the correct size and heaviest load rating available.
Title: Re: Tires - Michelin 2004 U320 - Steer vs. Drive tires - 275/80R22.5 vs. 295/80R22.5
Post by: Pierce & Gaylie Stewart on March 18, 2021, 10:26:45 am
I understand wanting to have tires with an increased load rating and going to 16 ply will do the trick but in the existing size with a firmer ride. I have put larger sized tires on quite a few cars but even though the change only increases the tire radius just under 1/2 inch, it needs to be established that no damage can be done at any coach angle and loading while backing. Possibly, the cut could be adjusted so it would clear but I wonder what that would do to the coach turning radius?
So, staying with 80 aspect ratio at 295 size keeps 14 ply and a taller sidewall for a more comfortable ride while increasing the load capacity at lower pressures. But, FOT cannot recommend going to that size for legal reasons.
We are quite satisfied in the ride with ours at 110 psi all around but I see others may not be.
In case of a flat tire, the 295/75R22.5 is much easier to find while on the road if you don't carry a spare.
With our tires already polishing our airbag plates, I'm inclined to keep on the cautious side and let someone else give it a try. Remember, the coach was designed with the narrower 275/80R22.5 as the default tire. The 295/75 was a change that has proven successful with only a minor clearance issue.
Pierce
Title: Re: Tires - Michelin 2004 U320 - Steer vs. Drive tires - 275/80R22.5 vs. 295/80R22.5
Post by: cucotx on April 14, 2021, 08:35:54 pm
Done. I'm the happy owner of a 2004 Foretravel U320. A beautiful coach. My thanks to the previous owner for taking such great care of the bus. It is in great shape.
Now the fun begins. I'm inspecting for things that need fixing and/or any desired upgrades.
First of all, it turns out this coach is riding on Bridgestone R268 295/80R22.5 tires. The tires under discussion in this thread. But, even though the coach is riding with the bigger tires that I wanted, I'm not convinced yet that the 295/80 are appropriate for this coach.
There are no signs of dry rot or sidewall problems with the tires, but they're 6 years old, so I plan to change them right away. I'll replace with the same size if I'm satisfied that the 295/80s are appropriate. Eight tires and 6 Centramatic wheel balancers. That's the first big expense for the coach.
On a related note, I have noticed that the underneath of the wheel well for both tag tires show obvious signs that the tag tires have been hitting the wheel well. But, I don't think the 1/3" height difference between the axle and the top of the tire when comparing the 275/80 with the 295/80 would be to blame. It seems the shocks may need some looking into. Also, on my 10 hour drive after purchasing the coach, I noticed a lot of bouncing of the coach, more than would be reasonable. But, not sure how much bouncing is normal for the MH. The other wheel wells do not show any similar signs of tire hitting.
Any thoughts from others on this issue with the tag axle?
Title: Re: Tires - Michelin 2004 U320 - Steer vs. Drive tires - 275/80R22.5 vs. 295/80R22.5
Post by: dsd on April 15, 2021, 10:15:17 am
Done. I'm the happy owner of a 2004 Foretravel U320. A beautiful coach. My thanks to the previous owner for taking such great care of the bus. It is in great shape.
Now the fun begins. I'm inspecting for things that need fixing and/or any desired upgrades.
First of all, it turns out this coach is riding on Bridgestone R268 295/80R22.5 tires. The tires under discussion in this thread. But, even though the coach is riding with the bigger tires that I wanted, I'm not convinced yet that the 295/80 are appropriate for this coach.
There are no signs of dry rot or sidewall problems with the tires, but they're 6 years old, so I plan to change them right away. I'll replace with the same size if I'm satisfied that the 295/80s are appropriate. Eight tires and 6 Centramatic wheel balancers. That's the first big expense for the coach.
On a related note, I have noticed that the underneath of the wheel well for both tag tires show obvious signs that the tag tires have been hitting the wheel well. But, I don't think the 1/3" height difference between the axle and the top of the tire when comparing the 275/80 with the 295/80 would be to blame. It seems the shocks may need some looking into. Also, on my 10 hour drive after purchasing the coach, I noticed a lot of bouncing of the coach, more than would be reasonable. But, not sure how much bouncing is normal for the MH. The other wheel wells do not show any similar signs of tire hitting.
Any thoughts from others on this issue with the tag axle?
Congratulations on new coach. Over the road trucking is allowed to operate tire up to ten years old. Your old tires may have a resale value. Does your tag axle lift on your coach? May have caused spinning down retracted? Scott
Title: Re: Tires - Michelin 2004 U320 - Steer vs. Drive tires - 275/80R22.5 vs. 295/80R22.5
Post by: Roger & Susan in Home2 on April 15, 2021, 10:55:14 am
Here is a Michelin Ref for RV tires.
Loaded rolling radius for a 275/80R 22.5 LRH XLine Energy Z is 18.7" Loaded rolling radius for a 295/80R 22.5 LRH XZA2 is 19.1"
The distance rolled by the 295 per revolution is about 2.1% greater than for the 275. If your coach was setup for the 275 size then speed and miles shown will be less than actual. In 10,000 miles it will be off by 210 miles.
It is common for VMSpc users to ask about the difference between ECU reported miles and the dash gauge, they are always different. Loads, tire pressure altitude, temperature all play into the difference but they are rarely more than 1%. Changing to a different tire size will make a bigger difference
Title: Re: Tires - Michelin 2004 U320 - Steer vs. Drive tires - 275/80R22.5 vs. 295/80R22.5
Post by: Doug W. on April 15, 2021, 11:14:53 am
Over the road trucking is allowed to operate tire up to ten years old. Scott
Not sure there is a law on the books regarding older than 10 year old tires in commercial use.
How Long Can Your Commercial Truck Tires Last? - Green Towing Los Angeles (https://greentowing-losangeles.com/2020/07/06/how-long-can-your-commercial-truck-tires-last/)
Title: Re: Tires - Michelin 2004 U320 - Steer vs. Drive tires - 275/80R22.5 vs. 295/80R22.5
Post by: cucotx on April 24, 2021, 11:59:25 pm
Here is a Michelin Ref for RV tires. Loaded rolling radius for a 275/80R 22.5 LRH XLine Energy Z is 18.7" Loaded rolling radius for a 295/80R 22.5 LRH XZA2 is 19.1"
So my recent purchase of a 2004 4020 U320 has 6 year-old Bridgestone R268 295/80R22.5 tires. The R268 have a loaded radius of 19.4". The tire that I would like to start using is the Michelin X Coach H LZ LRH 295/80R22.5. That tire has a loaded radius of 19.3". As a side note, the X Coach tires mounted single have a load rating of 8270 lbs at 123 psi. R268 is 7830 lbs at 123 psi. The X Coach have a dual mounting load rating of 7160 @123 psi. The R268 has a dual load rating of 6940 at 123 psi. So the overall goal for using the X Coach with the U320 is to run them at under 100 psi and still meet the GAWR of the U320.
So the question remains, is it at all safe and practical to use the 295/80R22.5 tire size as a replacement for the stock 275/80R22.5 with a 2004 4020 U320?
1 - The first thing that I did with investigating this was to check for any signs of rubbing in the wheel wells and with the air bag mounting at all tire positions. My inspection of the U320 did not show any rubbing with the wheel well or air bags for the steering and drive axle positions. It does come close, so it may be "polishing" the air bag support bracket. It may just be that it is not leaving any obvious visible signs.
Both tag axle positions do show rubbing of the wheel well, but that may have other causes other than tire size, as per number 2 below.
2 - I have noticed that when the coach is leveled while parked, the top of the tire in the tag axle wheel well which is positioned up hill from the opposite tag axle does come very close to touching the wheel well. It's half an inch of spacing or so. In trying to balance the coach while parked, obviously the downhill tag axle bag is inflated more to raise that side of the coach, increasing the distance from top of that tire to the underside of wheel well. The bag in the uphill wheel well is somewhat deflated in the attempt to balance the coach.
In my opinion, this may be the cause of the signs of rubbing of the tag axle tire within its wheel well. That is, would it be possible for one of the tag axle tires to rub against the underside of its wheel well while turning in uneven ground and while the tag axle is lifted?
3 - An obvious question that I thought about, and which continues to bother me is this: Are there sensors in place or would it be possible that the leveling system won't be able to realize that there is a bigger tire installed and thereby end up with the bottom of the wheel well resting on the top of the tire instead of balanced appropriately by the air bags? That is a scary thought!
Thanks in advance for any help with this. ^.^d
Title: Re: Tires - Michelin 2004 U320 - Steer vs. Drive tires - 275/80R22.5 vs. 295/80R22.5
Post by: craneman on April 25, 2021, 12:50:00 am
The air bags will keep the same distance no mater what tire is on, so a larger diameter tire will get closer to the floor. Not sure how much depends on the 1/2 distance of the larger diameter difference of the tire.
Title: Re: Tires - Michelin 2004 U320 - Steer vs. Drive tires - 275/80R22.5 vs. 295/80R22.5
Post by: wolfe10 on April 25, 2021, 07:43:28 am
Just to mention again, 295/75R22.5 is a very close match to the 275/80R22.5.
Might want to solicit comments from those who have gone that route.
Title: Re: Tires - Michelin 2004 U320 - Steer vs. Drive tires - 275/80R22.5 vs. 295/80R22.5
Post by: Chuck & Jeannie on April 25, 2021, 08:29:24 am
3 - An obvious question that I thought about, and which continues to bother me is this: Are there sensors in place or would it be possible that the leveling system won't be able to realize that there is a bigger tire installed and thereby end up with the bottom of the wheel well resting on the top of the tire instead of balanced appropriately by the air bags? That is a scary thought!
You are giving the HWH leveling system credit for intelligence it doesn't possess. There are no sensors to tell it what tire size is fitted. Correct ride height is the same regardless of tire size.
If you put a tire that is taller or wider than OEM stock on a coach, it will be more likely to touch, hit, or rub on something that is unyielding. Might be a serious problem - might not.
Title: Re: Tires - Michelin 2004 U320 - Steer vs. Drive tires - 275/80R22.5 vs. 295/80R22.5
Post by: bbeane on April 25, 2021, 09:02:32 am
I run 295 75 22.5 Toyo tires, very little polishing on the airbag seats, they do touch with the air dumped the 75s are very very close to the 275 80s why would you want to go all the way up to 295 80 that are quit a bit larger. With a tag coach a LR H tire should be plenty.
Title: Re: Tires - Michelin 2004 U320 - Steer vs. Drive tires - 275/80R22.5 vs. 295/80R22.5
Post by: cucotx on April 25, 2021, 09:51:12 am
1 - I was checking the maintenance records for the coach. It turns out both shocks for the tag axle were replaced about 6 months ago. That could account for the signs of rubbing of the tire in the wheel well. You can definitely learn a lot about a used coach by checking the repair records for it.
2 - What I think I'm going to do is stick with the 275/80R22.5 tire size that was designed into the coach by the smart people at FT. It may be safe to change to 295/75, but there would be no gain in the load rating for those tires, so why do it. The bottom line is that I really don't know enough about the coach to make a wise decision. And I don't have enough time to test for acceptable safety prior to buying the bigger tire.
I have purchased a TPMS with 12 sensors (coach and toad) and plan to install 6 Centramatics wheel balancers for all coach axles. The new tires, once properly inflated, the TPMS and the Centramatics should be good enough to roll down the road safely. In the meantime, I have plenty of other things to immediately fix and enhance in the coach, e.g. new chassis and house batteries, new FET battery isolators, proper multi stage dc-to-dc chargers for both the chassis and the aging AGM house batteries.
Thank you all. Great feedback and help from the knowledgeable Foretravel community. Much appreciated.
Title: Re: Tires - Michelin 2004 U320 - Steer vs. Drive tires - 275/80R22.5 vs. 295/80R22.5
Post by: Pierce & Gaylie Stewart on April 25, 2021, 09:56:06 am
What I think I'm going to do is stick with the 275/80R22.5 tire size that was designed into the coach by the smart people at FT.
Bit of a oxymoron to me. Some were smart, some missed the boat entirely.
Pierce
Title: Re: Tires - Michelin 2004 U320 - Steer vs. Drive tires - 275/80R22.5 vs. 295/80R22.5
Post by: Protech Racing on April 26, 2021, 11:51:17 am
Keep in mind that taller tires will accelerate and decelerate slower. The CG will raise and the coach will be slightly more susceptible to wind movement. Fuel mileage will suffer a little also as the tires weigh more and the effective gear is taller . The exception is the 4 speeds that can use a little more gear , like my 88 , Cat .
Title: Re: Tires - Michelin 2004 U320 - Steer vs. Drive tires - 275/80R22.5 vs. 295/80R22.5
Post by: Pierce & Gaylie Stewart on April 26, 2021, 12:37:35 pm
Fuel mileage will suffer a little also as the tires weigh more and the effective gear is taller .
A taller gear ratio should give better fuel mileage not worse. Piston travel is less per mile. It's like a slight overdrive. Our U300 could use a little taller ratio in 4th but a taller ratio would give slightly slower acceleration.
Pierce
Title: Re: Tires - Michelin 2004 U320 - Steer vs. Drive tires - 275/80R22.5 vs. 295/80R22.5
Post by: Michelle on April 26, 2021, 12:52:46 pm
Just to mention again, 295/75R22.5 is a very close match to the 275/80R22.5.
Might want to solicit comments from those who have gone that route.
Bumping Brett's comment about a potentially more appropriate size alternative to the 275/80R22.5
Title: Re: Tires - Michelin 2004 U320 - Steer vs. Drive tires - 275/80R22.5 vs. 295/80R22.5
Post by: Protech Racing on April 26, 2021, 01:19:45 pm
Fuel mileage will suffer a little also as the tires weigh more and the effective gear is taller . The exception is the 4 speeds that can use a little more gear , like my 88 , Cat . The reality is that it may be a wash . The taller heavier tire needs more throttle angle for the same V vs the taller Inches per revolution.
In my case the OE speedo read 9% high , Now the GPS speedo read DFN. 2300RPM is 63 MPH.
Title: Re: Tires - Michelin 2004 U320 - Steer vs. Drive tires - 275/80R22.5 vs. 295/80R22.5
Post by: Pierce & Gaylie Stewart on April 26, 2021, 02:24:49 pm
Fuel mileage will suffer a little also as the tires weigh more and the effective gear is taller . The exception is the 4 speeds that can use a little more gear , like my 88 , Cat . The reality is that it may be a wash . The taller heavier tire needs more throttle angle for the same V vs the taller Inches per revolution. In my case the OE speedo read 9% high , Now the GPS speedo read DFN. 2300RPM is 63 MPH.
Weight does not have much to do with it except for a slight difference in rotating mass when starting or stopping and only a tiny, bit. Yes, you do have to open the throttle slightly more but the decrease in piston travel per mile more than makes up for it.
Here is a primer for gear ratios vs MPG. The Pinto/Mustang photo says it all: Advance Auto Parts - Down for Maintenance (https://shop.advanceautoparts.com/r/advice/car-technology/get-to-know-gear-ratios-and-how-they-affect-acceleration-and-mileage)
Now, anytime you change the aspect ratio, you do put more surface on the road which can increase the rolling resistance and lower the mpg slightly. But if the aspect ratio stays the same, the taller tire will get better mileage. So, a 295/75R22.5 will use a little more fuel than a 275/80R22.5 because of more square inches of rubber on the road. But lower aspect tires have shorter sidewalls so flex less and have slightly less rolling resistance because of less flex.
In flying, my twin used 31 gallons per hour so once I got to cruising altitude, I would increase the bite on the props with lower RPM so I could lower my GPH to about 25 and going further per gallon. A little slower but more than made up for it in less fuel burned. Remember the film, The High and the Mighty? That's how they got to San Francisco.
Now, how do you compare a 4.1 to 1 vs 2.73. to 1? The car with the 4.11 will always accelerate faster but going on a trip, it will always burn more fuel in the same distance traveled. Increasing the tire diameter will always decrease the engine RPM and the distance in feet the pistons travel per mile. Tire weight has nothing to do with it in the real world. Changes to the gear ratio or the tire diameter will always change the engine speed.
Pierce
Title: Re: Tires - Michelin 2004 U320 - Steer vs. Drive tires - 275/80R22.5 vs. 295/80R22.5
Post by: cucotx on April 26, 2021, 10:23:03 pm
Ok. I can't give up this easily.
Here is a new plan: Since I need new tires anyways, I will buy two of the Michelin X Coach 295/80R22.5 and install them for the steering axle. If it turns out they hit anything under the wheel well, they come out and get moved into the tag or drive axle. I would then buy the smaller 275/80 for use in the steering axle and forget about this whole idea for good.
Question: I would like to cover the edge of the metal mounting bracket for the air bags and the underside of the wheel well for the steering axle with something that will show that there is interference. What can I use for this test? Chalk?
Does anyone know the upper limits of the onboard air compressor? Is it 120 psi? The reason for asking this is that I would like to use the onboard compressor to air up the tires. It will be a lot easier to air up the X Coach 295/80 tires to 100 psi from the onboard compressor than 115 psi or higher when using the 275/80 stock tires.
I have built this whatchamacallit thingy for airing up the tires: https://www.youtube.com/watch?v=n5fK54DKWP0
Title: Re: Tires - Michelin 2004 U320 - Steer vs. Drive tires - 275/80R22.5 vs. 295/80R22.5
Post by: "Irish" on April 26, 2021, 11:24:40 pm
Paint the brackets with spray paint, if it wears off you will see it , if not you will have repainted them. Win win situation Good luck David PS: drive tires make more road noise than steer tires
Title: Re: Tires - Michelin 2004 U320 - Steer vs. Drive tires - 275/80R22.5 vs. 295/80R22.5
Post by: craneman on April 27, 2021, 12:46:34 pm
Here is a new plan: Since I need new tires anyways, I will buy two of the Michelin X Coach 295/80R22.5 and install them for the steering axle. If it turns out they hit anything under the wheel well, they come out and get moved into the tag or drive axle. I would then buy the smaller 275/80 for use in the steering axle and forget about this whole idea for good.
Question: I would like to cover the edge of the metal mounting bracket for the air bags and the underside of the wheel well for the steering axle with something that will show that there is interference. What can I use for this test? Chalk?
Does anyone know the upper limits of the onboard air compressor? Is it 120 psi? The reason for asking this is that I would like to use the onboard compressor to air up the tires. It will be a lot easier to air up the X Coach 295/80 tires to 100 psi from the onboard compressor than 115 psi or higher when using the 275/80 stock tires.
I have built this whatchamacallit thingy for airing up the tires: https://www.youtube.com/watch?v=n5fK54DKWP0
I added a second ball valve so it can be used as a gauge without hooking up air.
Title: Re: Tires - Michelin 2004 U320 - Steer vs. Drive tires - 275/80R22.5 vs. 295/80R22.5
Post by: MisterEd on April 27, 2021, 10:39:21 pm
Does anyone know the upper limits of the onboard air compressor? Is it 120 psi? The reason for asking this is that I would like to use the onboard compressor to air up the tires. It will be a lot easier to air up the X Coach 295/80 tires to 100 psi from the onboard compressor than 115 psi or higher when using the 275/80 stock tires.
I have built this whatchamacallit thingy for airing up the tires: https://www.youtube.com/watch?v=n5fK54DKWP0
If you have this compressor, as does ours, 100PSI is the limit. THOMAS 1/10 hp HP Piston Air Compressor, 12V DC, 100/100 Max. PSI Cont./Int.... (http://www.grainger.com/product/THOMAS-1-10-hp-HP-Piston-Air-Compressor-5Z349?cpnuser=undefined&searchBar=true&searchQuery=405ADC38%2F12&suggestConfigId=6)
If you're talking about the engine driven compressor, 120-125 PSI, depending upon the setting of the governor. Our governor is set to 125PSI and it takes a long time to inflate over 100PSI. To get the tires over 100PSI you have to finish airing the tire just before the governor unloads the compressor.
Greg
Title: Re: Tires - Michelin 2004 U320 - Steer vs. Drive tires - 275/80R22.5 vs. 295/80R22.5
Post by: craneman on April 27, 2021, 10:56:35 pm
I set mine to 130 makes airing the tires much easier.
Title: Re: Tires - Michelin 2004 U320 - Steer vs. Drive tires - 275/80R22.5 vs. 295/80R22.5
Post by: cucotx on May 13, 2021, 07:50:40 pm
Order for 6 Centramatics wheel balancers for the bus.
From Centramatics Tech Support: - For the steering tires: Part 700-720. A pair for $199. - For the drive axle: Part 600-640. A pair for $215 - For the tag axle: Part 600-640. Since the tag axle has disc brakes and the rim is the same as that for the drive tire, it is the same number.
Total of 6 for all three axles (including shipping): $659. They have a backlog of orders right now, so ETA for delivery is about 3 weeks.
When ordering from Centramics. Their technical support group will need the following info:
Year, Make and Model of coach Wheel size Tire size Number of studs Is it DRUM or DISK brakes for the front axle? Steel or aluminum wheels? If you have a tag, they'll want to know if that rim looks like the drive wheel or the steering wheel? They also wanted to know if the tag axle had disc or drum brakes.
For my U320, the wheels are: - Steering, tag axle and outer drive: 22.5 X 8.25 Alcoa Aluminum #883643DB - Inner drive wheel: 22.5 X 8.25 Accuride Steel Wheel #50408
Title: Re: Tires - Michelin 2004 U320 - Steer vs. Drive tires - 275/80R22.5 vs. 295/80R22.5
Post by: cucotx on June 14, 2021, 08:43:57 am
I set mine to 130 makes airing the tires much easier.
How/Where do you set the engine driven compressor Governor HIGH setting to 130?
Title: Re: Tires - Michelin 2004 U320 - Steer vs. Drive tires - 275/80R22.5 vs. 295/80R22.5
Post by: cucotx on June 14, 2021, 08:50:20 am
I'm ready to pull the trigger and replace the 8 bus tires. But, I'm still not convinced that the 295/80R22.5 tires can be used for the steering axle in place of the stock 275/80R22.5. I'm not interested in the 295/75R22.5 size either. The reason for the initial interest in the 295/80R22.5 was to get the higher load capacity tires in order to operate at a lower psi.
So I have decided to install 275/80R22.5 Michelin X Line Energy Z LRH for the front axle and Michelin 295/80R22.5 X Coach HLZ LRH for the tag and drive axles.
Update: The X Coach HLZ LRH tire is no longer available. Discontinued by Michelin.
Title: Re: Tires - Michelin 2004 U320 - Steer vs. Drive tires - 275/80R22.5 vs. 295/80R22.5
Post by: bbeane on June 14, 2021, 08:54:01 am
Oh no, not the tire size thing again 😬😬. You might try the Search function, much discussion on this very subject.
Just curious why would you mix tire sizes, as your 275s would be sufficient all the way around.
Title: Re: Tires - Michelin 2004 U320 - Steer vs. Drive tires - 275/80R22.5 vs. 295/80R22.5
Post by: cucotx on June 14, 2021, 09:01:58 am
Just curious why would you mix tire sizes, as your 275s would be sufficient all the way around.
1 - I think the X Coach HLZ LRH tire is a better tire than most 275/80.
Update: The X Coach HLZ LRH tire is no longer available. Discontinued by Michelin. Replacement is the Michelin X Coach Z (#53962)
2 - With a higher load rating, I'll be able to run them at a lower psi setting than 275/80 while also taking full advantage of the maximum drive and tag axle weight ratings. Also, airing up the 275/80 to 115 psi or so with the onboard compressor is a pain. The 295/80 tires will air up a lot easier because of the lower needed psi for the same axle loading.
3 - But, I do think that the 275/80R22.5 is the needed tire size for that U320 front axle, as designed.
Title: Re: Tires - Michelin 2004 U320 - Steer vs. Drive tires - 275/80R22.5 vs. 295/80R22.5
Post by: craneman on June 14, 2021, 09:07:25 am
How/Where do you set the engine driven compressor Governor HIGH setting to 130?
ISM D2 Air Governor is located where? (https://www.foreforums.com/index.php?topic=38982.msg381648#msg381648)
https://www.youtube.com/watch?v=kXIdL6Xh7ko
Title: Re: Tires - Michelin 2004 U320 - Steer vs. Drive tires - 275/80R22.5 vs. 295/80R22.5
Post by: Rudy on June 14, 2021, 10:14:08 am
Peter, are purchasing your tires from Dave Ward, National Tire Concierge Service, which less than FMCA? Plus road hazard warranty included along with Michelin On-Call.
Title: Re: Tires - Michelin 2004 U320 - Steer vs. Drive tires - 275/80R22.5 vs. 295/80R22.5
Post by: cucotx on June 14, 2021, 10:31:29 am
Peter, are purchasing your tires from Dave Ward, National Tire Concierge Service, which less than FMCA? Plus road hazard warranty included along with Michelin On-Call.
I did. No price difference from that of FMCA but hazard warranty and Michelin On-Call worked for me. Plus, Dave worked hard to see if he could locate inventory of the X Coach tires for me. That was welcomed.
Title: Re: Tires - Michelin 2004 U320 - Steer vs. Drive tires - 275/80R22.5 vs. 295/80R22.5
Post by: bigdog on June 14, 2021, 03:16:43 pm
we had replaced our old Michelin RV sized tires (275/80/22.5) with the wider 295/75/22.5 Toyo's and also had MoT replaced the airbags. I asked about the rubbing of the mounting plate. They said 'DO NOT WORRY ABOUT IT'
The steering angle required to have contact with that plate is such that it will only happen at slow speeds. That much input at highway speeds will have you on your side.
Title: Re: Tires - Michelin 2004 U320 - Steer vs. Drive tires - 275/80R22.5 vs. 295/80R22.5
Post by: Pierce & Gaylie Stewart on June 14, 2021, 06:16:34 pm
we had replaced our old Michelin RV sized tires (275/80/22.5) with the wider 295/75/22.5 Toyo's and also had MoT replaced the airbags. I asked about the rubbing of the mounting plate. They said 'DO NOT WORRY ABOUT IT' The steering angle required to have contact with that plate is such that it will only happen at slow speeds. That much input at highway speeds will have you one your side.
I just looked at our 295/75s and they didn't touch the air bag plate on our trip. Lots of lock to lock campground turns but we didn't go down any unimproved roads where we lean way over. That's where we get an occasional light contact. As everyone has said, don't worry about it.
Pierce
Pierce
Title: Re: Tires - Michelin 2004 U320 - Steer vs. Drive tires - 275/80R22.5 vs. 295/80R22.5
Post by: bigdog on June 14, 2021, 07:11:55 pm
I just looked at our 295/75s and they didn't touch the air bag plate on our trip. Lots of lock to lock campground turns but we didn't go down any unimproved roads where we lean way over. That's where we get an occasional light contact. As everyone has said, don't worry about it.
Pierce
Pierce
At the risk of ruffling a few feathers. This thread illustrates perfectly what I posted last week about tires and tire pressure. We RV owners have way to much time for extreme levels of researching. We often end up chasing our tails and lose sight of the big picture.
Which is: That one inch wider tire only results in half an inch width increase on the inner tire area that MIGHT cause some minor rubbing. And that rubbing will only happen at SLOW speeds. So it isn't actually a big deal nor an impediment to reversing. If one is constantly up against the steering stops. They might want to take some of that research time and use it to look at techniques on turning in tight quarters and prepositioning for reversing into a parking site. Prepositioning was a key ingredient in my commercial truck training. Bad prepositioning is the BIGGEST issue I see when folks get into a jam while reversing at RV parks.
Title: Re: Tires - Michelin 2004 U320 - Steer vs. Drive tires - 275/80R22.5 vs. 295/80R22.5
Post by: Pierce & Gaylie Stewart on June 14, 2021, 07:34:13 pm
BigDog,
Agree positioning at many RV Parks but in some super tight Sierra campsites, I'm lock to lock even with a spotter. We are frequently pushing branches aside even going forward. Making the turn on our driveway heading down requires full lock. I have to back up a quarter mile and at the steep uphill turn, I usually have to make two attempts to miss a tree and telephone pole.
I remember in Juárez, Mexico, I went down the wrong street and had to make 13 lock to lock turns to get around a T corner.
As I was the instructor that taught all the new (and some old) guys backing techniques at the fire department, I can understand your concern.
Pierce
Title: Re: Tires - Michelin 2004 U320 - Steer vs. Drive tires - 275/80R22.5 vs. 295/80R22.5
Post by: bigdog on June 14, 2021, 07:55:54 pm
Agree positioning at many RV Parks but in some super tight Sierra campsites, I'm lock to lock even with a spotter. We are frequently pushing branches aside even going forward. Making the turn on our driveway heading down requires full lock. I have to back up a quarter mile and at the steep uphill turn, I usually have to make two attempts to miss a tree and telephone pole.
I remember in Juárez, Mexico, I went down the wrong street and had to make 13 lock to lock turns to get around a T corner.
As I was the instructor that taught all the new (and some old) guys backing techniques at the fire department, I can understand your concern.
Pierce
Not so much concern Pierce. Just something for folks to think about. Your many multiple point turn situation is probably not common among the Foretravel crowd.
I see so many folks pull up with their wheels a foot or two from the edge of the site they want to reverse into. Then proceed to turn the wheel till I can hear their PS pump squealing. Then that is followed by the partner waving their arms wildly and much yelling ensues. All they had to do was turn slightly away from their site as they pull forward. Thus making the angle much less than 90 degrees. Or even going around to position themselves for a drivers side reverse instead of on the blind side.
It is very entertaining. If I don't think I will get shot or punched in the nose. I will offer some guidance at some point. But with all the short tempered people out there. I mostly just watch and never make rude comments or point and laugh. That would be in very bad taste.
Title: Re: Tires - Michelin 2004 U320 - Steer vs. Drive tires - 275/80R22.5 vs. 295/80R22.5
Post by: cucotx on June 15, 2021, 09:46:15 am
Does anyone know of a 295/75R22.5 steer tire with better than 7160 lbs maximum rating when used as a single tire, as with the front axle?
If so, I would use that size for the steering axle in place of the 275/80. I just can't find a 295/75 with higher ratings than the 275/80.
Title: Re: Tires - Michelin 2004 U320 - Steer vs. Drive tires - 275/80R22.5 vs. 295/80R22.5
Post by: Rudy on June 15, 2021, 09:59:03 am
Peter, 295 75R 22.5 does not have the carry capacity of a 295 80R 22.5. The 80% sidewall is a tall, larger diameter, tire than the 75% sidewall. So the clearance problems with taller tire.
Now a 305 width tire is a little smaller in diameter than than a 295 75R 22.5 but has a lot more carry capacity and cost more too.
Title: Re: Tires - Michelin 2004 U320 - Steer vs. Drive tires - 275/80R22.5 vs. 295/80R22.5
Post by: cucotx on June 15, 2021, 10:15:28 am
Now a 305 width tire is a little smaller in diameter than than a 295 75R 22.5 but has a lot more carry capacity and cost more too.
I haven't heard of anyone here with a 305/70 for the steering tire in a U320. The 305/70R22.5 would be more than 1" wider than the OEM 275/80, but not as tall. I don't know if that extra width would be a problem.
So, I'm sticking with the FT recommended 275/80R22.5 and deal with the issue of airing up those tires with the onboard compressor and any perceived rougher ride of the 275/80
Title: Re: Tires - Michelin 2004 U320 - Steer vs. Drive tires - 275/80R22.5 vs. 295/80R22.5
Post by: Pierce & Gaylie Stewart on June 15, 2021, 10:32:54 am
Peter,
You have a front axle with a 13,880 or 14,320 lb capacity so need a tire with more than an H rated 295/75 can give you. You have probably watched the blowout on YouTube where the left front tire blew out and the coach was off the road in about one second. Not a pretty video.
So, how about a 305/70R225 like Rudy suggests? The diameter would remain about 39.5 to 40 inches so would be the same as a 295/75. The load capacity would be 7826 to 8050 lbs. per tire. You would then have a safety margin over the capacity of your axle.
If you went to a Toyo, Firestone, Bridgestone with a better casing than the Michelin has, the price would be about the same as the 295/75. Here is an example: TOYO M144 305/70R22.5 152/148L L20 (https://www.tiresdirect.net/toyo-m144-305-70r22-5-152-150l-l20.html) The $487.92 is just the first example I found in a couple of seconds. If you used an independent supplier like I did, the price would be less. These suppliers buy directly and fill a container so are able to offer much better out the door prices than places like Walmart, etc. So, for a reasonable price, you get a better tire.
Pierce
Title: Re: Tires - Michelin 2004 U320 - Steer vs. Drive tires - 275/80R22.5 vs. 295/80R22.5
Post by: cucotx on June 15, 2021, 12:13:18 pm
Tires ordered.
The Michelin 295/80R22.5 X Coach LHZ LRH tire is obsolete (Catalog # 31078). The new "equivalent" tire is the Michelin 295/80R22.5 X Coach Z LRH (Catalog # 53962). 8270 lbs @ 123 psi Single and 7390 lbs @123 psi dual. I bought 6 of those for the tag and drive axles from David Ward at NTCS for $693.23 each.
For the steering axles, I bought 2 of the 275/80R22.5 Michelin X Line Energy Z LRH (Catalog # 66205). 7160 lbs single @ 120 psi and 6610 lbs dual @ 120 psi. I forget what the price was for that one.
Title: Re: Tires - Michelin 2004 U320 - Steer vs. Drive tires - 275/80R22.5 vs. 295/80R22.5
Post by: cucotx on June 28, 2021, 05:35:05 pm
Tires Installed.
6 Michelin X Coach Z 295/80R22.5 for drive and tag axles. 2 Michelin X Line Energy Z 275/80R22.5 for steering axle.
6 Centramatics wheel balancers installed.
1 - The coach does ride much better with the Centramatics. It is subtle but it does seem to have a "smoother" ride.
2 - Pictures of new X Coach Z tire.
3 - Picture to show difference in spacing between air bag in front axle and both 275/80 and previous 295/80.
4 - Picture of Centramatics sitting on tag axle hub.
For now, until I get the coach weighed, I have the steering tires set to 120 psi, the drive at 100 psi and the tag at 75 psi.
Title: Re: Tires - Michelin 2004 U320 - Steer vs. Drive tires - 275/80R22.5 vs. 295/80R22.5
Post by: Ed W on June 28, 2021, 05:52:00 pm
Your fronts are already installed, but for future reference, I had Michelin 295/80, XZA2 ENERGY installed on our front last summer. No rubbing issues. I installed these so I could run lower pressure (100 psi). I still have 295/75 Toyo's in the back. Not sure if I will use the 295/80 in the front in 4 years or go back to the 275/80 Michelin. The 100 psi is much easier to attain than 117 psi.
The 295/80 Michelin's are quieter and smoother than the Toyos they replaced. Maybe partially due to the lower pressure.