Foretravel Owners' Forum

I was wondering what would be recommended on my coach for tire pressure front and back. I'm heading in for service and than they can check my tires .
Looking forwards to your response 
Rob

If you don't know what each axle actually weighs or better what each corner weighs (with a tag drive and tag) then it is best to set the pressure at the pressure recommended by the tire manufacturer for the gross axle weight rating.

If you do know weights then use the highest of the two sides of an axle to set the pressure recommended by the tire manufacturer plus 5 lbs but not more than the max pressure.

I run close to max in the front because I think it is safer.  Others may think differently.

Roger

I know my weights and still run max psi. more pressure = sharper handling, less worrying, and lower tire temps.

some sit aroudn and calculate psi based on weight. I run max recommended and drive. no worries. its been great for the 6k miles ive driven in 3 months of ownership on ancient 2007 tires.

I have always maxed the pressures without figuring the load since the sixties. Handles great, stops well and tires run cool.

Pierce

Max pressure equals poorer traction and more severe loads on suspension.  Get your coach weighed and run the tire pressures recommended by the tire manufacturer.

It's slightly rougher ride at max (which I ran when I first bought my FT)

I run 100psi all around. It makes it simple to check, no wondering what axle is what. I installed Crossfires too....easy to keep eye on pressure: Amazon.com: Crossfire Dual Tire Pressure Equalization System, 100 PSI, one... (http://www.amazon.com/Crossfire-Dual-Pressure-Equalization-CF100STABT/dp/B0003040ZS/ref=sr_1_1?ie=UTF8&qid=1441635570)

Max is 110 on my tires. 9600lbs front, 1800 lbs rear. Tossed all my notes, but 100 gives good safety margin for both front and rear.

My Best Practice ... Weigh each axle and each end.  Set tire pressure accordingly with a fudge factor.

I run 106 in the front and 96 across the single back based on mfr pressure/load charts + 5 psi.

We were just out in OR for a month.  Someone posted that their weigh station scales remained operational even if the station was closed.  They were right.  I checked axle weights twice (very consistant) and the right side once to get four corners.

L-R in the rear were within 50 lbs.  L-R in the front about 200 lbs heavier on the drivers side.  Scales read to the nearest 50 lbs.  Easy and free.

Have not redone my old test I did hundreds of times when running the old ca Foretravel store as sales manager but it seemed to work then.

After countless discussions with highly opinionated owners some knowledgeable, some not so  much about this I thought I found a way to help quantify on a quick term basis whether the air pressure in the coaches tires was correct.

Here's what we did. 

Found nice white concrete and wet it to make a puddle and then drove through it onto a dry area.

As the tire(s) dried out and driving in a radius so the paths did not cross the pattern used to show lighter on the edges with higher pressure.

Zero idea if this works still.  Better engineering now might keep the tire flatter at all normal pressure variations?

Lots of interest back then so took a drive in countless coaches to test them.  Fairly sensitive back then.  Five pounds easily changed the dry out pattern.

Oh of course a tire thread depth wear gauge works well to check wear?

I totally agree with Amos and would never run my tires at anything other than the charted weight/versus pressure that the tire maker recommended.

That being said if the mpg is for various reasons the most important thing to an owner running max pressures definately adds mpg.  At least long ago.

Foretravel delivery drivers would call me and ask if they could increase the tire pressure for the 1369 mile drive to my store as it made them $20 more as Foretravel filled the tank for the drive out.  Any refills were on them.

Foretravel shipped the coach with the tires matched to the weighed empty coach back then.

I find on the internet that my new tires are good for around 250,000 miles on an 18 wheeler to go from 19/32 thread depth to 6/32" which I understand is the minimum you should run.

So 12/32" over 250,000 miles won't show much short term on a tread depth gauge but over long enough some may be able to quantify the pressures they are using with actual facts?

Unless the engineers have gotten so good as to have identical across the tires wear regardless of the pressure which I doubt.

Be nice if a bunch here would buy a cheap gauge and measure their tires to help all of us here?

Opinions are nice but I prefer facts.  Did this long ago with hundreds of owners.

Guess it's time again.

Running long ago on the center rib as was posted made a rougher ride and the coach handled funny and wandered more in winds.

Tire tech and better shocks might cover this up anymore and the pressure variations may make zero wear differences. 

But I doubt it.  If enough here show me a full contact wear patch and exactly the same handling and ride quality at a pressure over the manufacturers charts I like everyone here would like better mpg as long as no safety issues or ride quality reductions are the penalty.

Five dollar tire thread depth gauge would add lots to any tire pressures mentioned would it not?

My old tires were all over the map on wear. 

When you say the tires last 250,000 miles are you including miles after regrooving? My Michelin XZE 275/80 R22.5 tires measure about half worn with 30,000 miles on them. Last summer I saw a similar tire on the front of a fairly new garbage truck with 46,000 miles on it and the mechanic replaced it because he said it was worn out, but it still had over 1/16" tread on it. Garbage trucks do a lot of tight turns but this tire didn't have any strange wear patterns. The mechanic didn't think 46,000 miles was an abnormally short life for that tire... so I was thinking my tires would go somewhere between 50,000 - 100,000 miles. Yes, I already know my tires are old and everyone on this forum thinks I should replace them, but I'm gonna run them until they wear out. They don't even have any weather cracks. At the rate I've been traveling I'll probably wear them out as soon as three years from now... unless they really do last 250,000 miles?

Washington State has the same deal. I don't see many scales in our travels, but checking with a friendly State Patrol officer might be of help.

They had A WEIGH WE GO at the last grandvention in TN.  They weighed us as we were leaving.  It was a great deal.

After weighing with my 2 scooters, which will make me the heaviest on the front axle, so I run 115 on my fronts.  I should be 110 but I add 5 pounds.  My rears I have at 100 and the tag at 90.

As far as the wear miles I going by the over the road truckers report of miles.

Matches the Michelin warranty of 7 years/700,000 miles with the carcass being good for three redoes.

Search Xza-3's or maybe it was on the Michelin website as far as owners reports.

A lot commented on that kind of life.

Obviously the exact setup and use can change this to a great extent.

Half the reason I spent the money for the Michelin's were these reports and the high value for dated but low wear tires in the future.

My tire guy says they use them for runouts on trailers.  In other words use up the tread versus worry about recapping them.

I would think 100-200k on tread for a good quality tire is to be expected for long haul over the road.

Amen to that. I blew a cap one time; it scared the pucky out of me!  >:D

I just measured my new Michelin spare that's never been used and it has about 19/32" tread according to my dial indicator. My six Michelins with about 30,000 miles on them average about 15/32" on them. So I guess you're right and they should last longer than 100,000 miles at this rate. Darn it, I was hoping to be the first RV owner in the history of the world to wear out a set of tires.

I enjoy reading about folks who KNOW that XX psi is correct but add 5 psi for good measure. Kinda makes me thing that the XX psi sinn't correct. ^.^d

Hey Larry, a little wiggle room helps some times.  We left 100+teens in Montana at 6,500'  for sea level and 50's - 90's in Oregon to 32° this morning at almost 7,000' in the Tetons in four weeks.  When we head south in the winter I air up for ambient temps in MN (-30° Feb, 2014) and two days later it is 70°.  I had to let air out every day.  0-5 psi over spec is OK with me. A little overinflated is better than under inflated. 

I have load range G tires soon to be replaced with LRH.  A little more air in the LRG stiffens up the sidewalls some.  Won't need it so much with the LRH tires.

Tire story ...

A guy in an older Prevost pulled in near us a few days ago.  Coach seemed to straighten up to level and plumb until engine was turned off then sagged as I watched to about 4" off level side to side.  Then he gets out some ramps made from 6x8 and proceeded to drive the front tire on one and the outside rear drive tire on another.  Nothing under the inside drive and nothing under the tag.  6x8 was about  3" narrower than the tread width.  I have neve seen a side wall bulge like his rear tire did. I really expected it to just blow out.  He left today. Good luck with that tire.

So now let's talk about your leaving in -20 temps. Roger, my boy, gotta get going sooner. I was in MN for three winters in the 70's and leave for Florida in early October. Don't like cold!

It was -30°, really.  We are OK with the cold up to a point.  It is pretty miserable adding air to all six tires at -30°. With the coach in the barn (or as Brad M calls it, the coach house), the AquaHot on preheating the engine for a day or two and the inside of the coach as well, the exhaust out throught the side port in the barn and the coach plugged in, starting is easy.  We let it warm up a while while final connections are made with the toad, lights are checked, the barn is locked the house is double checked and we are off slow and easy for about 15 - 20 miles to let stuff start to move and limber up.  And then we are off.  Of course it takes two days before the long johns come off.

For us it is all about the weather on our route south.  Cold is OK, it is only two days to warm.  Ice or snow?  We just stay put and wait for a few days.  Never in a hurry here.

Might be cold in the winter in MN but the summers are nice.  Visitors are welcome.

reminds me of a time I blew a front right steer on a bridge...best Bridgestone tire money could buy! luckily noticed a little bulge in the side wall about the size of a half a pencil while at a lumber mill loading green timbers destined for Puget Sound Naval Shipyard. While crossing a bridge in  Olympia headed for the tire store instead of taking the on ramp to I-5 northbound she blew! luckily for the foot and a half curb held me from going over the rail...

That's right Mike,  hard to know how someone will react sometimes especially when they think what they are doing is just fine.  If they ask for my opinion I will say something otherwise stay out of harm's way.

Thank you for the factual info.

How's the wear pattern?  Straight across?  What pressure versus weight?

If I had a ten spot for every tire pressure discussion I have had with rv owners I would have a much newer coach.

Used to the snickers from the pros who know better.  Countless times.  Foretravel ships every coach since the 80's set for the weight as far as I know. 

And fmca weighed coaches and adjusted the pressure to match the load on each tire since the 80's.

But what do they know.....

Radial vs bias ply? That makes a difference on how the tire sits?

That extra five psi is for insurance.  Just in case of a slow leak, more loading, or lower cold temperatures.  Safer to be high than low.

"How's the wear pattern?  Straight across?  What pressure versus weight?"

There's no wear pattern, it's evenly worn straight across on all six tires. When I checked my tires during preflight inspection when I last drove it two days ago the front tires were 106 psi and the rears were 102 psi. It's a 36' U300 lightly loaded and the tires are rated for 110 psi. I haven't weighed my coach. I'm sure it's nowhere near the 30,000 lbs stated on the data plate. I haven't experienced any tire problems except a leaking schrader valve which was replaced immediately when I noticed it during preflight inspection over two years ago. I always always always check my tires along with several other important items before I even start the engine.

I saw the exact same tires as mine, same size and everything, on the front of a tow truck in Santa Fe. It's the tow truck with Mighty Mouse on the side of it. Maybe someone on this forum has noticed it? The tires are badly weather cracked but have about the same tread depth as mine. All the mechanics at Hal Burns were standing there so I asked them if those tires were safe with that amount of weather cracking. Their response was unanimous, every single one of them said the same thing... Anyone care to guess what their response was? ...I should have taken a photo of the tires with my cell phone! haha

tow truck company probably bought them at the tire store second hand...off the fancy motorhome just ahead of him.

Had a Canadian couple staying with us in Yuma a couple of winters ago with a Newmar wanted to buy new tires in the U.S. to save a few bucks. The tire store did not want to give him anything in exchange for his old tires plus wanted to chg. for disposal. I advertise on Craigslist, trucker meet us at the store...win win for both parties!!

But that tiny surface crack that goes 1/100th of the way into the sidewall is bad news.

Thanks Scott for the factual info. 

I hope others will report on their actual wear, weight and pressure and what exact tires they are using.

Would seem to be a useful thing for the forum to have a pinned or some other way to have a easily accessible file for the info.  Being as it is one of the most expensive things for our coaches.

My tires varied from each other on the rear by up to 6/32nd's

And we're up to 6-7 32nd's off across the tread. 

Zxa–1's

Obviously not carefully cared for as far as alignment by a previous owner before the barks.

On my five year old dated tires the steel belts  were exposed.  The tire guy was surprised.

Desert home in the past I understand.  At least for the first year on the 2010 tires on the rear.

Fronts were ten years old with similar depth cracks?  Who knows?  Bad chemicals on the sidewalls?

Gingerly drive the coach to get new shoes.

What is the consensus for storage.  Tire guy mentioned about no concrete.  Others say asphalt?

Get a moisture barrier between whatever you park on long term and the tires.  Remnant sheet vinyl flooring works good.  I got mine free.  Home Depot usually has them at low cost and you can get matching pieces.

Folks who store their Corvettes over the winter get curved plastic ramp like things that are the same radius as the tire.  Tires sit in them supported in the curve rather than the flat.  No thumping tires.  I thought about this idea, it would be easy to make from some left over LVL. You still want to isolate the tire from a wooden ramp.

Many of you have seen it in another Forum thread probably — or you already know from having been at past GrandVentions — but there will be the opportunity to have coaches weighed in Columbus, IN, on October 17.  Made our appointment today. 

Since we are newbies, we want all the info we can get.  Grateful for everyone's perspective in this thread. 

One post in this thread was interesting, re: there being a market for tires removed.  We took off two perfect-looking Michelin XZA3 steer tires last month, because they hit 8 years. I'd heard from a guy in the park where we're staying that he sold his to a local tire dealer for $100 each because farmers, who remain local and drive slowly, put them on trailers.  No luck.  Called 4 dealers.  Best I was offered was $50 for the two tires.  Three other dealers didn't want them.  Since the tires were taking up all the space in the largest bay of our coach, it was worth more to Susan & me to get the bay back to its normal contents, than to rent a small trailer and drag the tires down to the dealer.  Maybe we missed a better deal?

I got $75 each for the 6 Michelin take offs, they were about 5.5 yr old.  The Michelin dealer was delighted to get them, very little wear at 50,000 miles. Good tires are good insurance to me.

Michelin and bandag have age limits on tires that can be recapped. I think it is 7 years.

Might be the case with Michelin casings

How Long Do Truck Tires Last? - Tire Review Magazine (http://www.tirereview.com/how-long-do-truck-tires-last/)

Thanks, all.  Dave M — I'm with you.  Good tires are good insurance.

For what it's worth, a friend who is an exec with a tire company, and has run some of their truck tire plants, says 7 years.  He even replaces the spare in his car at 7 years.  Granted, if I were a skeptic, a tire company exec would have reason to recommend replacement (sells more tires). But he's a friend, too.  If I understood (no guarantee that's so), his reasoning seemed to be that after 7 years — no matter how good they look from outside (sidewall condition, tread depth, etc.), they begin to deteriorate from the inside.

Inherent moisture trapped during the manufacturing process affecting the steel belts?  I dunno!  Never made a tire.  Just know I've seen too many blowout films.  http://www.youtube.com/watch?v=9LkLeljt4t0

I'd like to point out that there are upper limits to aie pressure also.  I blew the sidewall out of a 2 yr old xza3 lrh using a combination of clip on chuck, the 120 lb governed air supply of coach, and head firmly up aah...not paying attention.

Chuck,

The upper limits where a tire will explode according to the Bridgestone Truck Tire site are more than twice the maximum pressure listed on the side of the tire. Here is Bridgestone's quote: In actual tests, modern truck tires can often be inflated to over twice their maximum rated pressure before failing.Plus, most wheels break down before the tire does.

Your tire had some kind of previous damage for it to explode.

Pierce

Chuck, I'll agree with Pierce on this. you're "not paying attention" skirted you from having a expensive and dangerous blow out on the road.
Here's an example of a rim giving out under pressure.
http://www.youtube.com/watch?v=Q-3U-TRkJx8&feature=youtube_gdata_player

I used the original 50 year old bias ply spare tire in my 1965 Impala a couple of years ago on the freeway in Dallas... no really! :) ...it's still in like new condition and I'm still alive

We just put six new Michelins on our coach last month, the steers were '02 XZE's and the drives were '04 & 05 XZA1's. We bought it that way and they were way over due. All had cracking.
Replaced with 275/80R/22.5 XZE's

One tire dealer told us that max life on car and light truck tires should be 5 or 6 years and heavy truck tires 7 to 10 years max. Depending on how the tires were used and cared for, driven a lot or stored and sheltered or exposed to the elements. Not all tires age the same. Another tire dealer insisted that 5 years should be the max on all tires. Two different dealers can't agree, only thing in common other than both were Michelin dealers was they both make a living off of selling new tires.

What I take from this is "change you tires between 5 and 10 years".  :-\
New tires can blow out at any time, but the older they are the greater the chance that they might.

Actually, I'm kind of glad to hear this, I'd been kicking myself for ruining a good tire.  Though they drive well my Michelin experience has not been good.

A few tidbits for tire age, retreads, etc:

Bridgestone-Firestone has a lot of tire info online. They have about the best reputation for the quality of casing construction of the major manufactures in reading quite a few tire forums. I was surprised to find out that well over 50% of replacement tires are retreads. Bridgestone in the PDF also states that the tires in the survey are between 10 and 15 years old.  Also, the cracks we see in the sidewall are from ozone and unless badly cracked as seen in some of the photo examples, are not a reason to reject a tire.

http://www.ncleg.net/documentsites/committees/JLTOC/2011-12_Biennium/Archive/2008-04-23/Presentations/Tire%20Retread%20Study/How%20Long%20Do%20Commercial%20Truck%20Tires%20Last.pdf

This is an excellent article with good insight into tire lifespan and the amount of retreads on the road. A good read for an RV owner.

In reading between the lines, Bridgestone has a much different take on tire lifespan compared to local dealers. Wonder why dealers recommend replacing sooner?  >:D

Pierce

Mine blew out at 8 years. Steel braids inside rubber were rusted, and I expect that caused failure

That's one reason why nitrogen inflation is supposed to be better, since most air that's used for inflation is actually rather wet.

The Michelin shop that replaced my 6 only does the nitrogen, interesting that after a year they have not lost any psi even with the Pressure Pro screwed on em.

Aircraft propeller unfeathering accumulator tanks get only nitrogen. With coach air, a dryer in the hose to the air chuck will keep the moisture to a minimum. A lot of gas stations never drain the water from their compressor tanks. Either way, dry is good.

Our fire trucks never had dryers and always spit out quite a bit of water when drained during each morning's warmup.

Pierce

Is not the air line output in our coaches from a source after the air dryer?

Bob,

I keep an extra dryer in the line as can be seen in the attached photo below (gold at the top of the photo). Since I keep all the tires at 110 psi, I don't want to wait for the engine compressor to cycle so keep a contractor's compressor ready to go for tires or the coach air system if the engine failed and it had to be towed. It goes much higher and will run the big impact if needed. I also keep a large diameter air supply hose and a tank with a short hose to the 1" impact. Photo #2 shows the stainless accumulator tank with the large quick connect I use for the larger air hose. The industrial strength 1" impact is just visible behind and to the right of the air jack.

Yes, the air at that location from the engine compressor is dry or at least, should be.

Bob, you're still pretty sharp. Was wondering how long it would take someone. ;-)

Pierce

Pierce, I run Michelin Super singles on my semi. I get about 259k out of them treadwise. Out of about 9 Virgin casings I have sent in for recapping 1 has actually passed their test and been capped all other casings were rejected. the one I had capped lasted 38,000 miles when it let go. So after a after hrs service call,$250.00 and the new tire 956.00 plus the cost of the failed retread 450.00 I should have bought a new Virgin. All I run is Virgins anymore I sell the casings to the tire shop,, Most of my issues are sidewalls blowing out. If something penetrates the tire casing,and is not discovered or it exits. the penetration will let the air pressure inside the tire go in between the belts and separate them usually forming a bulge in the sidewall. Then boom it lets go. It is really important to inspect tires for nails etc and remove them. If they do penetrate the tire casing it needs to be repaired from the inside with a plug patch. this type of repair will keep the air inside the tire.I also carry a plug kit with me but after using a plug to get going again I have the tire repaired with a plug patch soon after.

How long will that little tank run a 1" impact wrench?

I only use "Big Bertha" on stubborn lugs and in fact, have not had to use it at all on our U300. The tank is almost always connected to a compressor supply hose and the bigger hose is used to cut the friction loss so the big gun will run at full power. Your probably noticed the tank has 3 female fittings. I use a double male to allow air into the tank from the supply line or to charge it if I want to carry the tank to another location.

Since I always keep a coating of anti seize on the threads, I only torque to a little less than 300 lbs so any decent half inch air gun will take the nuts off very quickly. If I ever win the lottery, I will buy a little Milwaukee electric impact. They will take almost anything off.

Stump, yes, inspection will catch a bulge where air has gotten past the belts and is just waiting to pop the side. YouTube has some sidewall blowouts. I have had some big ones on my tractor rear tires. Even at 22 psi, they make a huge noise. Bridgestone says rubbing against curbs can cause damage aside from pot holes. Also, that under inflation is the cause of many of the "road gators" we see on the highway.

Tubeless plug kits are really good to carry and should (have not tried a plug yet) work on an airbag with a normal leak. When my airbag failed, it could have been easily fixed with a plug. As it turned out, I was able to drive it home and fix it.

Pierce

So I finally got an opportunity to weigh all 4 corners of our coach (Oregon scales are always open and free) and its full of diesel, propane and almost full of fresh water. All holding tanks empty.

Heavy front was 4300 and heavy rear was 8800. Actually rear was same within 50.    According to the Michelin site  the 275/80 r 22.5 xze tire chart for weight doesn't even go that low. Starts at a couple hundred pounds heavier.

 The pressure for front and rear would come in at 75 lbs.      Does anybody else run that low of tire pressure. I haven't seen that pressure posted. Let me know before I start letting air out.
 

 Checked the tread depth with gage a few weeks ago and running about 2/32 more ware in center at 85lbs single and 90lbs dual.
  Tires are 3 years old and 19/32 average.

I would not run less than the recommended tire pressure on the I.D. plate, should be 85 single and 90 dual. When I installed new Michelin tires two months ago (same size LRH ) the tire shop wouldn't put less than 95psi and said that was the minimum they felt comfortable with in that size and H rating tire.

I have not had the opportunity to weigh the coach, so I have left the pressure at 95, though I feel I will probably lower the pressure a little after I know my actual weight.

Just be aware that the "recommended tire pressure on the I.D. plate" is based on each axle being loaded to its GAWR.

So, if you are near your axle ratings, that recommended PSI is very close.

But, if you are well under that weight .......

True ..... But, when you don't know your exact weight it is better to err on the high side rather than run overloaded and under inflated tires.

Totally agree.  Until you weigh, better to over than under inflate.

But, of course best answer is to weigh it and get it right!

In Bob''s case ..... His weight is below the minimum on the Michelin tire press chart. What then? How low can you go without being below the minimum safe inflation of the tire?

Do not go below minimum-- and that is what the tire charts say.

Said another way, minimum is minimum.

0 lbs below minimum

Thanks to all for the feedback.

  Weight on id tag for front is 10,000. I'm at 8200. And tag says 19,000 rear. I'm at 17,200 rear.

At least I won't be going with the max pressure on the tire at 110. I know that I won't be wearing the tires out either way. (Gonna try though)
  Just interested in getting the best handling and best ride possible. Looks like with 5lbs cushion I'll go with 80lbs.

80 psi may give you a softer ride but sure won't give you the best handling.

Pierce