Community Forums

Unicorn Driver · 06-02-2018, 08:41 AM

Hi,

Just purchased a Workhorse UFO gas coach on 255/ 80 r22.5 tires.

I am going to get it weighed today and check with Michelin but out interest I am wondering what pressure folks are running and what does your coach weigh?

Dealer has them 100psi but have crept up to 105psi in the heat.

Thanks,

Unicorn Driver · 06-02-2018, 09:16 AM

Got a weigh, I am 8000lbs on steer axle and 14380lb.

I did weigh with a full tank of gas and water.

Bob Hyatt · 06-02-2018, 09:22 AM

Quote:

Originally Posted by 1stmh

Hi,

Just purchased a Workhorse UFO gas coach on 255/ 80 r22.5 tires.

I am going to get it weighed today and check with Michelin but out interest I am wondering what pressure folks are running and what does your coach weigh?

Dealer has them 100psi but have crept up to 105psi in the heat.

Thanks,

My 24K 2018 Tiffin 32SA came in at 7380 on front, 13600 on rear, full tank of gas (80 gallons), 3/4 full fresh water, 1/3 full black, empty grey, with normal stuff on board (ie pads, chocks, cooking stuff, etc. No clothes or food, but I can't imagine that adding up to a significant addition.

I am running 80 PSI all around now, improved ride, no impact on handling, and that gives about a 1200 pound safety margin on front and 2000 pounds on rear, which won't be exceeded in any way I can think of...

Do run a TPMS for additional safety, which catches pressure changes and high temps.

We have a CAT scale about 4 miles from the house. Cost me $11.50 to get it weighed. My tires were also at just over 100 PSI. Feel the road cracks/joints MUCH less with a reasonable PSI.

I would not guess, however. Best to do it by the book and get it weighed.

Hooligan · 06-02-2018, 12:16 PM

Quote:

Originally Posted by 1stmh

Got a weigh, I am 8000lbs on steer axle and 14380lb.

I did weigh with a full tank of gas and water.

Figure your weight fully loaded to travel, passengers and all.

Michelin RV tire load tables https://www.michelinrvtires.com/refe...tion-tables/#/

Tables show load and inflation for an individual wheel single or dual. It is the minimum pressure required to support that weight.
Your front axle is 8000# the chart shows at 75psi the tires will support 4070# each or 8140 lbs on the axle. However you don't know if the weight is evenly distributed and to provide a little cushion I would recommend at least 80psi (4300#per tire) and possibly 85. (4400#/tire)

You can go into the chart and figure your pressure for the rear axle..

Unicorn Driver · 06-02-2018, 12:41 PM

Thanks Bob and Holligan,

I did feel that 100psi is a bit much. I do use a TPMS which I took from my last coach.

I have to figure out how much extra cargo, to be conservative I would say 250lb extra on the front and 500lbs on the back.

Unicorn Driver · 06-02-2018, 01:23 PM

A rough caluclation looks like 90pai in the rear ans 85 psi up front. I would like to get a 4 corner weight but none available around here.

bobmac · 06-02-2018, 01:44 PM

You really need to get/download a copy of the Michelin RV Guide and go the tire you have and determine the correct pressure. If you have axle weights, you should consider adding maybe 5 lbs to the recommended pressures as it is highly likely one side will be more than the other. I would rely on that rather than somewhat like myself telling you what I use. Good luck,

Unicorn Driver · 06-02-2018, 01:53 PM

Hi Bob,

I download the guide Hooligan posted, thats where I got my figures from.

I was curious as to what others are running at.

100psi dedinitley felt too much.