What tire pressure you running?

[ctusdenny]

I just purchased a National Dolphin MH a couple months ago. I haven't found a place to weigh it yet, so I'm wondering what others are using for tire pressures? I have the 22.5" XRV tires, with fronts at 90 psi, and the rears at 95 psi. I'd say the MH is moderately loaded as I have basically rid myself of the "nice to have" items, and simply keep the "must have" now.

Thanks.

[D M]

Hi Denny, I run 110 in front and rear better rolling for better fuel mpg, and less heat.


Don
2001 Rexhall Aerbus-36 ft.
spartan 330 cummins

[Mike Canter]

Denny until you weigh it you need to make sure that you are at or above the recommended gross vehicle weight recommended tire pressures which are normally on a decal that is on the wall next to the drivers seat or on the back of a closet door. I am sure that 110 psi is above the recommended tire pressures but that will give you a rough ride. I have tried upping the tire pressures in my MH to improve MPG and have seen zero change. Probably over a period of 10K miles there maybe an advantage but I would rather have the smoother ride.

If you go to this website you can get all the tire pressure and load data plus if you scroll all the way down you can download it.
Michelin Americas Truck Tires XRV® Page

[gfs1943]

Like you, I haven't got the MH weighed yet. I don't have much "stuff" in the MH, so I'm running with the manufacturer's recommended pressures of 100 psi front, 90 psi rear. Well - maybe just a couple psi over.

[Dynasty_09]

I agree with Mike,

Tire pressure and Weight go hand in hand. Before weighting my MH I was running 20 pounds too high and my tires were wearing in the middle. The ride was harsh too!

I always make it a must to stop and check my motorhome on a scale at least once a year (With and without the trailer!) to find if I'm not over GCWR(Gross Combined Weight Rating) or GAWR (Groos Axle Weight Rating).

So now, I'm running 100 Front/ 90 Rear without the trailer and 90 Front / 100 Rear with the trailer...

[ctusdenny]

Very good info. Thanks.

Where is a good place to weigh your MH? Do truck scales off the highways allow this? I live in Seattle, Washington, but haven't found a scale yet.

[Mr_D]

WA and OR usually leave the scales on when they're closed. Even Henderson's in Grants Pass uses them during their evaluation drive. All I do is find one that's closed and drive in.

[3wheeljunkie]

When you find a scale make sure you tell them that you dont need a certified weigh.
(a lot cheeper)

[flasher]

I use to run what the tire said,ride was bumpy and harsh,95psi,now I run what the coach sticker says,70 psi front and rear,rides much better and the tires wear evenly,I thought 70 psi was too low for a 35'Itasca,I guess the manufactures know what their doing

[sc3283]

denny, I don't have a Dolphin and can't give you a pressure to use but can say with my recent RV purchase.....
The 6 Bridgestones all looked perfect in every way when buying the RV. They had 33k miles on them. They were all aired to 110lbs. Weighing the RV showed me I could by the Bridgestone tire charts run 85psi frt and back. That was too low for my liking. I lowered all 6 to 100lbs...The ride drastically improved, the handling stayed the same. I contacted the previous owner about pressures..he always ran 110psi...so with 33k miles@110psi.....I'm curious as to what 100psi will do for wear..unfortunately the tire age has timed out and it will have 6 new tires on it this coming spring

[Arch Hoagland]

I run my 22.5's at about the same pressure as you. Mine is weighed and pressure set at what Michelin recommends plus about 5 lb.
I had new front tires installed, due to alignment problems, and the dealer set the pressure to 110 pounds on the front.. Drove from Fresno, Ca to Sacramento, Ca and promptly dropped the pressure back down to 90 lbs. Terrible ride at that high of a pressure plus there was a bit of wandering.
The recommended pressure is where they should be set for overall use.

[ctusdenny]

I finally found a truck scale where I was able to weigh my coach. Unfortunately, there wasn't room on the sides to weigh each tire seperately, but I did weight the fronts and rears.

Front weight = 7,280
Rear weight = 12,640

So...if I divide them equally (yes, I realize the weight is likely not distributed equally), I get 3640 and 6320 respectively.

Now, when taking the weights, I had a full tank of fuel on board, plus about 30 gal. of water and nothing in the waste holding tanks. Furthermore, I had 4 people in the coach, and a very small amount of gear. Not knowing exactly, I would estimate the gear to be around 300 lbs conservatively.

If I look at Michelin's XRV pressure table, for my 235/80 R22.5 tires I see that I could run the fronts and rears at 80 psi and still have quite a bit of wiggle room on weight. That seems quite low to me, but I'm no tire expert.

If I bump up another 5 psi maybe? Right now, the tire center inflated them to 100 psi since we didn't know the coach weight at the time. I can tell you it's a %^$&* rough ride at that pressure.

[Chuck 1935]

One thing that has not been mentioned in all of these tire pressure debates is tread depth. If you use a tread depth guage and measure the tread across the tire, it will give you a good indication of wether or not you are under or over inflated. If the center of the tread is thinner than the tire edge, you have too high a pressure etc.

[Hipshot]

When I bought my Bounder it had 95 all around. It handled good but was a little harsh, it was also empty. I loaded it for travel, food, fuel, 2/3 tank of water, clothes, etc. Did a 4 corner weigh and according to the chart I could run 80 & 85. I tried those pressures and the MH felt mushy and did not steer as well. I upped the pressure to 90 all around and all is good. It handles good again and the ride is not as harsh as it was at 95. Based on my experience I would advise never go under what the charts say based on your weights or over the max cold pressure stamped on the tires. But you can go over the chart pressures to improve handleing.