Tire Pressure Survey... of sorts

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Tire Pressure Survey... of sorts

August 18, 2011, 05:19:29 pm

As opposed to a discussion of tire pressures/tire manufacturers/coach weights, I'm more curious to know what tire pressures everybody is carrying in their tires.

For starters, I'm riding on Michelin XZEs.

Front 105 PSI
Rear 100 PSI

Re: Tire Pressure Survey... of sorts

Reply #1 – August 18, 2011, 05:24:31 pm

Russell, Continental 275 80 R22.5 HSL LRH at 110 PSI all the way around.
Gary B

Re: Tire Pressure Survey... of sorts

Reply #2 – August 18, 2011, 05:51:53 pm

Russell,

While answers could be of interest, I am a bit concerned that a Newbie to our site could conclude "what is good for another coach/most coaches is the right answer for me and my coach".

I know you know better, but one thing we need to be aware of is that we continually have new owners looking for information here.

For them (I know, off topic per your question): Weigh individual wheel positions. With the heavier wheel position on each axle, go to your tire manufacturer's inflation/weight table for your tire to determine the minimum PSI. Many add 5 PSI to that minimum for a safety allowance. If you only have axle weights (much easier to get) you might add 10 PSI to account for left/right imbalance.

Sorry for the off topic reply.

BTW, 95 front, 85 rear on Michelin 255/80R22.5 XZE.

Brett

Re: Tire Pressure Survey... of sorts

Reply #3 – August 18, 2011, 06:33:04 pm

Russell,

110 psi cold all the way around. 295/75 R22.5 Cooper CXMT 340A (with one Firestone thrown in) '93 U300 36 feet.

Re: Tire Pressure Survey... of sorts

Reply #4 – August 18, 2011, 06:59:42 pm

It's really going to vary according to load range of tires and weight of coach. Wayne at Foretravel, who aligned this coach was adamant that tire pressure be set by tire chart. That meant 85 psi front for my XZA3 lr H.

Re: Tire Pressure Survey... of sorts

Reply #5 – August 18, 2011, 07:22:14 pm

Yokohama 295/80/22.5
F105#
R100#

Re: Tire Pressure Survey... of sorts

Reply #6 – August 18, 2011, 07:40:15 pm

Russell =

Also XZEs, LRH, 4-corner weigh, then use Mich Chart and add 5#: front 90#; Rears 85#.

Re: Tire Pressure Survey... of sorts

Reply #7 – August 18, 2011, 07:45:15 pm

Why not take the average tire pressure, looks like it would be somewhere between 85 to 110, so where is panic ? Looks like anywhere between those numbers would be fine.
For me I run 100 Drive and 105 Steer, Tires are running cool, ride is fine, handling is fine, and tire wear seems non existant.
Yes I know I am not reading all the hype. I just can not get all worked up on this one.
FWIW

Re: Tire Pressure Survey... of sorts

Reply #8 – August 18, 2011, 08:03:38 pm

Depends on our loading.

Usually F100, R95, T75

For a major trek with more stuff (summers) F105, R100, T75

75 psi is the lowest listed pressure for the XZA3 LRH's and we are well under the 9830 lbs on our tag this pressure is rated for.

Michelle

Re: Tire Pressure Survey... of sorts

Reply #9 – August 18, 2011, 08:06:49 pm

Dave,

Let's take your range for the Michelin 295/80R22.5, a popular size.

Per Michelin (Michelin North America RV Load & Inflation Tables), 85 PSI can carry 5,940 pounds per tire single. 110 PSI can carry 7,300 pounds per tire single.

That's quite a range.

Re: Tire Pressure Survey... of sorts

Reply #10 – August 18, 2011, 08:19:55 pm

People that have worked in tire shops will never run low air pressure, they will stay to the upper limits. A rule of thumb in the old days is 10 psi per ply less one ply IE 12 ply 110 psi. If you use that rule you will have less tire issues.
Why everyone has an opinion.
Some good, some not so good.
When I have a tire getting soft, I can feel it. That is with out the P-P system.
Besides todays radial tires do not wear like the old bias tires, where you could look at the tire and tell is under / over inflated, that is much harder today with most radials.
Never said I was right , just opiniated, with some experience.

Re: Tire Pressure Survey... of sorts

Reply #11 – August 18, 2011, 09:03:12 pm

105 all around, XZA3 LRH's

Re: Tire Pressure Survey... of sorts

Reply #12 – August 18, 2011, 09:06:42 pm

I am running XZE s same as Russell. Front wheels weigh about 6,000# each. I run 97# in the front and 90 each on the duals. This give me a smooth ride and easy steering. DAN

Re: Tire Pressure Survey... of sorts

Reply #13 – August 18, 2011, 11:26:05 pm

Roadmaster RM180's (Cooper) was running 100psi all the way around because that's what the tire store put in. Problem was the coach was all over the road. On advice from someone on the forum (searched but couldn't find the post sorry to not give credit!) I lowered the tire pressure to 90 up front and the handling improved considerably.

I subsequently weighed the coach called Cooper and got the correct minimum tire pressure of 82 front and 90 rear. I added a couple of psi and I'm running 85 front and 95 rear (easy to remember). Coach tracks great now.

Moral is weigh your coach, check psi tables with manufacturer and experiment!

see ya
ken

Re: Tire Pressure Survey... of sorts

Reply #14 – August 18, 2011, 11:31:00 pm

Quote from: wolfe10 – August 18, 2011, 05:51:53 pm

BTW, 95 front, 85 rear on Michelin 255/80R22.5 XZE.

Learned something!!! Been going to ask for a long time, but now I know. What size tire to switch to from the 9R22.5.
Oh, I run the same tire pressure on the 9R22.5s.

Re: Tire Pressure Survey... of sorts

Reply #15 – August 19, 2011, 07:01:20 am

XZA3's LRH 110 front, 85 drive, 85 tag, 5psi margin, individual wheel weights.

Re: Tire Pressure Survey... of sorts

Reply #16 – August 19, 2011, 11:49:22 am

Front: 105 psi Michelin XZA3 275X80RX22.5
Rear: 100psi Michelin XZA2 275X80RX22.5

Front GAWR 13,880 weighed in at 12,500
Rear GAWR 21,000 weighed in at 20,320
Coach weighed with NO food, black and gray tanks EMPTY, propane 3/4 FULL and water and fuel tanks FULL.

Re: Tire Pressure Survey... of sorts

Reply #17 – August 20, 2011, 12:52:44 am

Foretravel weights - 11,360 steer axle, 18740 drive axle
Michelin 295/80R22.5 XZA2 Energy chart says: about 80-85 front and about 80 rear (that a tad higher than the chart, but where I settled). These are the tires that I bought recently when we bought the coach.

The Foretravel Manual gave for Michelin XA-2 Low Profile: 90 front and 75 rear. These may be different tires than I have and thus the small difference in psi they suggest.

I cannot explain the difference in these numbers versus some that cite the 100 - 110 psi but I did not study the weights they were running. I have weighed twice. I can report it drives very nicely with these; I measure the temp of the tires just to learn something but do worry I run too low given what some others say. Will talk to tire folks again but this from the chart with new tires. Maybe it just because our coach about 30,000 lbs.
Mike

Re: Tire Pressure Survey... of sorts

Reply #18 – August 20, 2011, 07:06:07 am

Mike,

The difference between the Foretravel manual/GVWR plaque in the driver's area and the tire pressure you are using based on your actual weight is easy to explain.

The Foretravel manual/GVWR plaque has tire pressure based on each axle being loaded to its GAWR (Gross Axle Weight Rating). If your actual weight is under that (sure hope it is), then the PSI on the plaque doesn't apply to your situation.

Brett

Re: Tire Pressure Survey... of sorts

Reply #19 – August 20, 2011, 05:02:39 pm

Michelin 275/80R 22.5 LRG, XZA2's 97 front, 87 drive.

Re: Tire Pressure Survey... of sorts

Reply #20 – August 20, 2011, 05:14:54 pm

This makes me wonder about the issue of tire pressure vs mpg. Since I always run about 110 in front and 105 in the duals, and I have always gotten good fuel mileage. Am wondering if others that run the lower (Correct ) tire pressure are also getting the good mileage ? I am curious if others running the ISM in a 36' towing a pickup are getting in the upper 8's average mpg? Just a question, I am certain many here keep real good records on such info, I do not, but know how mine runs.
More likely MPG is more related to how we handle the throttle, not related to tire pressure.

Re: Tire Pressure Survey... of sorts

Reply #21 – August 20, 2011, 07:24:58 pm

Dave M, On 3900 mile trip this summer I averages 8.2 for the whole trip. I run 110 PSI all around. I can't tell any difference in ride and I have never had a tire problem.
Gary B

Re: Tire Pressure Survey... of sorts

Reply #22 – August 20, 2011, 08:29:10 pm

Gary,

I'm a firm believer in max. listed psi = good fuel mileage and long life. Your 8.2 mpg is right in the ball park with mine for a long trip. My tires are never hot and the ride is OK for California. A warm or hot tire only gets that way by flexing and that generated heat uses extra diesel spinning them it down the road.

Our responses considered public safety first. We always ran 110 psi cold in our 11.00s. They stopped well (perhaps a dozen very hard braking applications a day) in wet or dry, cornered well and I never heard of any tire issue in all my years (or my dad's). All this with up to 10,000 lbs. of liquid on board (most high up).

Running a tire at manufacturer's maximum pressure does NOT result in a smaller footprint but maximizes that designed footprint in emergency stopping or evasive maneuvers by minimizing the distortion and deflection.

Hot weather, hot roads and hot tires don't go well together in a heavy vehicle anywhere close to it's gross weight.

Re: Tire Pressure Survey... of sorts

Reply #23 – August 20, 2011, 08:39:06 pm

Pierce, Total agree, I know from my P-P readings how the pressure goes up on a hot day as much as 10 psi or more, maybe I should start saying we all need to stop and bleed off some of that excess pressure ? That is what I call a Hoot.
I do love this subject.

Re: Tire Pressure Survey... of sorts

Reply #24 – August 20, 2011, 08:48:07 pm

100 front with toyos, 90 rear michelin

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