It Must Be The Tires?

Topic: It Must Be The Tires? (Read 843 times) previous topic - next topic

It Must Be The Tires?

July 11, 2016, 02:30:11 pm

Back in December I had six new Continental 275/80 R22.5 (H)tires put on our coach.

In the past I have had Michelins and Goodyears with good results on different coaches. Don't like the dry-rot feature of the Michelins, and was talked out of the Goodyears using price comparison.

We are driving a top-of-the-line coach now and the ride on these rough NE roads is unbelievable......... worse than our old Itasca. So bad that the wife wants to fly home rather than ride in this rig.

It's not a shock or handling issue, but more like the tires are too inflated, making them hard. I'm running the minimum PSI for the weight;
110 front and 100 rear.

I notice that both the Michelins and Goodyears call for 5lbs less PSI at this weight, but I can't believe that little difference will improve the ride much.

Really bummed out, because it's like this nice MH is going to be ruined from driving on poor
roads.

Re: Horr

Reply #1 – July 11, 2016, 02:34:04 pm

Been driving on Continental 275/80 R22.5's for five years and had no complaints or problems. We run between 85 and 90 psi basedd on our weights and like the ride. I believe them to be vey good tires.

Re: It Must Be The Tires?

Reply #2 – July 11, 2016, 02:37:18 pm

Ride harshness can certainly be overinflation, but can also be improper ride height. If too low, the coach can bottom out over bumps, and that will give a harsh ride.

Quick and easy to check (without getting dirty).

Re: It Must Be The Tires?

Reply #3 – July 11, 2016, 02:43:15 pm

Larry, what do your front and rear axles weigh?

Brett, the coach isn't bottoming out, just telegraphing every bump, crack or pothole.

Re: It Must Be The Tires?

Reply #4 – July 11, 2016, 03:44:47 pm

Just to eliminate them,are the shocks the original?

Re: It Must Be The Tires?

Reply #5 – July 11, 2016, 04:01:16 pm

Quote from: Traveling Man – July 11, 2016, 02:30:11 pm

Back in December I had six new Continental 275/80 R22.5 (H)tires put on our coach.

Did you (and DW) find the ride satisfactory before you installed new tires? If affirmative, then what was brand/type of old tires?

Re: It Must Be The Tires?

Reply #6 – July 11, 2016, 04:08:55 pm

You've GOT to have all four sides weighed, and see what the tire mfgr. suggests. We run new Michelin 255/80R/22.5 /XRV with Brett's great KONI shocks and Torsilastic Suspension. Glides along perfect with around 70 psi. That being said, we were coming back back from Death Valley and entered I-10 at Blythe, CA eastbound. Prolly THE WORST stretch of highway ever! It felt like I was driving my '47 GMC ton&half. Roads are crummy these days , the best thing to do is know what your weight on all fours is, shocks are a big deal!

Re: It Must Be The Tires?

Reply #7 – July 11, 2016, 04:35:02 pm

T-Man,
I agree with Mike, you need to get your coach weight at each corner.
110 front and 100 rear sounds like a lot of air for a 36 ft U295.

Re: It Must Be The Tires?

Reply #8 – July 11, 2016, 04:35:52 pm

Quote from: Chuck & Jeannie – July 11, 2016, 04:01:16 pm

Did you (and DW) find the ride satisfactory before you installed new tires? If affirmative, then what was brand/type of old tires?

I only drove on the original Michelins about 350 miles after purchasing. The Continentals were
better on roads in Tennessee and Florida.

Re: It Must Be The Tires?

Reply #9 – July 11, 2016, 04:39:22 pm

Quote from: John Duld – July 11, 2016, 04:35:02 pm

T-Man,
I agree with Mike, you need to get your coach weight at each corner.
110 front and 100 rear sounds like a lot of air for a 36 ft U295.

I have weighed the coach twice: 12,440 lbs front
and 20,000 lbs rear.

See post #3; Smart Weigh

Re: It Must Be The Tires?

Reply #10 – July 11, 2016, 04:50:34 pm

Quote from: Caflashbob – July 11, 2016, 04:48:58 pm

Divide the weight on each tire per the scale. Calculate the percentage of the max single and dual load you actually have.

If, for example you are 80% of the load be 80% of the max pressure.

My U320 40' is 100 front 90 rear.

You may be at upper 90's front and upper 80's rear.

Buy a accurate gauge. Verify the gauge.

I'm there.

Re: It Must Be The Tires?

Reply #11 – July 11, 2016, 04:58:41 pm

Quote from: John Duld – July 11, 2016, 04:35:02 pm

110 front and 100 rear sounds like a lot of air for a 36 ft U295.

We had tires replaced on the road by a Goodyear outlet, that was the pressure they suggested. The coach rode like hell. Finally stopped at another dealer who weighed the coach and said, "some idiot suggested the wrong pressure."

Re: It Must Be The Tires?

Reply #12 – July 11, 2016, 05:17:26 pm

I'd like to run 85 PSI, but every calculation and tire inflation chart calls for 95 lbs rear and 110 lbs front.

Re: It Must Be The Tires?

Reply #13 – July 11, 2016, 05:54:35 pm

Go with the tire manufacturer's inflation table FOR YOUR TIRE AND YOUR ACTUAL WEIGHTS. No percents, extrapolations, etc! If all you have is axle weights assume 45/55 weight distribution. Use the 55% side to go to the inflation table. And as recommended, at your first opportunity, get individual wheel weights.

Continental 275/80R22.5:

psi 70 75 80 85 90 95 100 105 110 115 120

Dual
lbs 4095 4300 4540 4690 4885 5070 5260 5440 5675 (G) 5795 6175 (H)

Single
lbs 4500 4725 4940 5155 5370 5510 5780 5980 6175 (G) 6370 6940 (H)

Re: It Must Be The Tires?

Reply #14 – July 11, 2016, 06:42:02 pm

Quote from: Traveling Man link=msg=238

Really bummed out, because it's like this nice MH is going to be ruined from driving on poor roads.
[/quote

.

I think it's the road surface, our coaches can only take so much and then we feel it...

Had the same experience this Spring on California roads headed North. Did my best to avoid the breakups but still It was so rough I took out the innards of a rear ride height control valve.

Re: It Must Be The Tires?

Reply #15 – July 11, 2016, 07:51:00 pm

T-man, you must haul around a ton (or 3) of stuff. My 270 full fuel, fresh water, empty grey/black is 10,500 front and 17,100 rear. We are not F/Ters so we travel light. Perhaps you could carry only the essentials and drop your tire pressure 10 psi which will make a BIG difference. I reset my tire pressure after I weighed it and could not believe what a difference 10 psi less made.

Re: It Must Be The Tires?

Reply #16 – July 11, 2016, 08:17:38 pm

Quote from: Traveling Man – July 11, 2016, 04:50:34 pm

I'm there.

You weigh the same in each axle on our 40' m11 non slide.

I assume the "h" rating from the Michelin's is similar to the conti's "h"

If that is true then my calculated and tested is as I said.

slightly "squirmy' handling in sharper high speed turns. Then it settles in and arcs beautifully.

Adding five pounds like the chart says might make it turn even better but I have not tested it.

Regarding the sharp response on bad roads the other part of the equation is the shocks.

Not sure how stiff the Bilsteins are but the industry all had this problem enough for Koni to build a special FSD shock that bypasses the main internal valving on square edges.

Separate circuit for slow speed stuff.

Defintely noticeable. Even over twice readjusted std Koni's

Stiff enough to help swaying added to the rough ride on square edges.

Cure was the FSD's in our identical weight coach

And 90/100.

On the road the easy one is the pressure of course

Re: It Must Be The Tires?

Reply #17 – July 11, 2016, 08:44:12 pm

I really do not doubt t-mans weights and calculated pressures. This is a 2003 36' with two slides. Not that much different than my 2003 38' with one slide.

It could be the tires. I sold my previous sob mh because Michelin stopped making that size, and the replacement brand was worse than horrible.

It could be the shocks, but they didn't change.

It could be an inaccurate tire gauge, but this is easily tested at a tire shop

And by the way, many owners and too many tire shops use the max pressure stamped on the sidewall as gospel, which is insanely wrong.

Re: It Must Be The Tires?

Reply #18 – July 11, 2016, 09:01:38 pm

Tom they cannot be sued if inflated to the sidewall pressure.

Re: It Must Be The Tires?

Reply #19 – July 11, 2016, 11:27:17 pm

CYA - yes

Good ride or handling - no

Re: It Must Be The Tires?

Reply #20 – July 12, 2016, 09:34:07 am

T-Man, last I weighed was 9100 on front and 18300 on rear. We don't travel heavy having been full-timig for almost 16 years. We've gotten real on what we need and dumped the rest. Good Luck.

Re: It Must Be The Tires?

Reply #21 – July 12, 2016, 10:31:33 am

Quote from: lgshoup – July 12, 2016, 09:34:07 am

T-Man, last I weighed was 9100 on front and 18300 on rear. We don't travel heavy having been full-timig for almost 16 years. We've gotten real on what we need and dumped the rest. Good Luck.

I'm never going to find a way to shed 3300 lbs up forward, but wish I could.

Re: It Must Be The Tires?

Reply #22 – July 12, 2016, 10:35:46 am

Quote from: Caflashbob – July 11, 2016, 08:17:38 pm

You weigh the same in each axle on our 40' m11 non slide.

Bob,
What tires are you running and at what PSI?

Re: It Must Be The Tires?

Reply #23 – July 12, 2016, 12:02:25 pm

I have the continentals too. I don't believe the ride is rough so much that a lot of noise and vibration is transmitted through. My personal feeling is that if I got under and adjusted the shocks firmer it would help to solve the issue. I run my fronts at 100psi. I do have complaints about the ride but that is compared to my Lexus GX470 which also has air suspension. I rode in a Wanderlodge and that was a lot worse than my Foretravel so I think all is well. It sure does handle the large bumps very well, it's just the little expansion joints that are jarring. My stepfather's renegade which had spring front suspension absorbed those much much better.

Re: It Must Be The Tires?

Reply #24 – July 12, 2016, 12:11:07 pm

Quote from: Traveling Man – July 12, 2016, 10:35:46 am

Bob,
What tires are you running and at what PSI?

Michelin xza-3+ evertreads "h" rated at 100 front. 90 rear

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