Motorhome Tire Pressure

smokey5209 · 06-07-2010, 10:08 AM

Folks

Need some more of your suggestions.

I recently put 6 new Michelin 235/80R22.5 XRV tire on my motorhome a 2003 Pace Arrow.

Today I had the coach weighed, loaded the way we travel, no water in the tanks, full fuel tank and LP gas.

I was unable to get individual weights per tire here in my area.

My coach weighed as follows:

Front Axle: 6,160 lb
Rear Axle: 13,720 lb
Total weight:19,880 lb

I called Michelin and spoke to Evelyn, she stated to run my tires at 75 lb front and 85 lb rear. She said this was with a 5 lb saftey or fudge factor.

I am seeking your opinions as this actually seems kind of low.

Thanking you in Advance
Ed

DriVer · 06-07-2010, 10:33 AM

Quote:

Originally Posted by smokey5209

I called Michelin and spoke to Evelyn, she stated to run my tires at 75 lb front and 85 lb rear. She said this was with a 5 lb safety or fudge factor.

smokey5209, She actually gave you a bigger fudge factor that what I calculated for the front axle however that said, the recommendations that she offered are valid.

Now do you know what your GAWRs are fro both F & R?

Luv2go · 06-07-2010, 10:38 AM

We have a chassis with similar measured weights and the Michelin charts recommend similar low pressures. We found that with 75lb in the front we were affected by wind, semi's passing, etc much more than when we used higher pressures. We now run 90lb in front and 100lb in the rear.

In general, people like to reduce tire pressure because of ride concerns, i.e. too harsh. We, for example, do not have this problem. It helps that my critic is comparing the ride to our old class C coach which rode like a dump truck with no load!

The tires can be run anywhere from the recommended values for your position or axle weights (like the ones you got from Michelin) to the sidewall limit (I believe it is 110lb in this case). Of course this is "cold" pressure, the pressures can be much higher after you have run them for a few miles (in our case 10-15 lb higher).

bdaball · 06-07-2010, 12:03 PM

Smokey5209,
Where ever you end up with pressures, give considerations to a tire monitoring system,(TPMS). There are several brands. The important thing is pick one and go with it.

OBTW, TST TPMS is a sponsor of this site.

DriVer · 06-07-2010, 05:27 PM

Quote:

Originally Posted by bdaball

OBTW, TST TPMS is a sponsor of this site.

bdaball, Or you could have simply said .... "OBTW, TST TPMS IASOTS!"

smokey5209 · 06-07-2010, 05:40 PM

Driver
Front Axle - 8,000 lb
Rear Axle - 14,500 lb

DriVer · 06-07-2010, 05:53 PM

Quote:

Originally Posted by smokey5209

Driver
Front Axle - 8,000 lb
Rear Axle - 14,500 lb

OK You must have edited your GAWRF while I was posting.

With those GAWRs I might think about going with 90psi F and 90psi R. Try that and take 2 aspirins and call me in the morning!

I have the 8,500F and the 15,000R and I run 90R and 95F.

bdaball · 06-07-2010, 07:24 PM

Quote:

Originally Posted by driver

bdaball, or you could have simply said .... "obtw, tst tpms iasots!"

hsicftmo!!

DriVer · 06-07-2010, 07:47 PM

Quote:

Originally Posted by bdaball

hsicftmo!!

OK ..... Now that's a little cryptic!

maxchord · 06-08-2010, 02:21 PM

I've been dealing with TP issues on my 2006 Monaco Monarch which I ran at 95F 90R - and the ride has been very harsh. The Michelin web site posts recommended pressures for the 235/80R22.5 XRV tire that are quite a bit less. My GAWR is 8,000F and 14,500R. Loaded to those levels, Michelin's recommended TP's are 85F&R, give or take a few pounds, and the recommendation given to Smokey5209 is per the chart +5psi front and back.

I'm now running 80psi F&R (not fully loaded) and have fitted the Koni FSB's to the front. The difference is dramatic, no longer is the front axle trying to smash it's way into the cab (the PA roads are in a realm of their own), and my chiropractor bills should go down. I think running higher TP's may give comfort of mind, but the ride deteriorates very rapidly above about 85psi.

Al