Tire Pressure Questions on my Michelin XRV 255/80R22.5

[dotcommer]

I was wondering the proper way to calculate proper tire inflation based on the manufacturer's ratings.

I currently have the Michelin XRV 255/80R22.5

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BELOW IS THE MANUFACTURERS SPECS
Per the Michelin website
Max Load Per Tire Single 5205/110 lbs/psi
Max Load Per Tire Dual 4805/110 lbs/psi

Loads per Axle End

PSI SINGLE,lbs DUAL,lbs
75psi 4070 7410
80psi 4300 7720
85psi 4440 8080
90psi 4620 8410
95psi 4805 8820
100psi 4975 9050
105psi 5150 9370
110psi 5205 9610
------------------

I had my coach weighed at a truck stop with a full load during my trip two weeks ago. This is the results

Steer Axle : 8020 lb
Rear Axle: 15840 lb

Questions:
Do I take steer axle weight of 8020lbs and divide it by 2 so it's at 4010lbs per tire? And the same for the Rear Axle 15840/2= 7920

Those numbers seem too low for tire inflation based on my weight especially since my total gross weight was 23860lbs which I believe is the max for my Thor Challenger 37tb

Any feedback would be great, thanks.

[roam1]

those 22.5 tires have a lot of carrying capacity! Thats why 80-85# seems low, but it isnt!

[Sam_Spade]

dotcommer wrote:
Thanks for all the info and clarification. I have had my tires at 100lbs when hot with the current load. It just seems they look low when visually looking at them.

Well, that's probably because they ARE low.

You should NEVER set the pressure in your tires when HOT.

I would say that you should never even measure the pressure hot.....but that can be useful in some circumstances.

[dotcommer]

Thanks for all the info and clarification. I have had my tires at 100lbs when hot with the current load. It just seems they look low when visually looking at them.

[DrewE]

Executive wrote:
Really, if you divide the rears by 2 and use the chart or divide by 4 and use the chart, they come out the same. I'd run 85# front and rear....Dennis

The weight capacity per tire for duals is always derated some relative to singles; and so the weight rating in the dual column is not twice that in the single column. While it may come out the same (or close enough to the same) in this case, that's not always true. For example, if the rear axle had 19,000 pounds on it: the correct pressure using the duals column would be right at the top, around 110 psi, but using the singles column you'd figure only 95 psi.

[Sam_Spade]

mccsix wrote:

I always put lower press on the rears because there are 4 tires carrying the load vs 2 front.

You didn't think it through far enough.

Sometimes the rear duals are located such that they carry twice the weight (or more) than the fronts do.

Your assumption might be right.....but it might not too.

[Executive45]

Really, if you divide the rears by 2 and use the chart or divide by 4 and use the chart, they come out the same. I'd run 85# front and rear....Dennis

[mccsix]

Thinking out loud here.
I always put lower press on the rears because there are 4 tires carrying the load vs 2 front.
Front carries the eng/tranny weight and us.
Always travel with empty tanks.
After weighing and charting...... 85# front, 80# rear.

[Sam_Spade]

STBRetired wrote:
Nope. Divide by 2 and then compare to weights in "Dual" column.

The information posted is confusing:
"Max Load Per Tire Dual 4805/110 lbs/psi"
But then the chart appears to be "per pair" for duals.

[DrewE]

MountainAir05 wrote:
Should not the 15840 be divided by 4 for the number of tires on the rear.

The particular chart being quoted is for "load per axle end", not "load per tire." I've seen load per tire on other charts, though, and obviously for that case the rear axle weight would be divided by four rather than by two.

[STBRetired]

Nope. Divide by 2 and then compare to weights in "Dual" column.

[MountainAir05]

Should not the 15840 be divided by 4 for the number of tires on the rear.

[Sam_Spade]

dotcommer wrote:
And the same for the Rear Axle 15840/2= 7920

IF....you have duals on the rear, 4 wheels total, then you would divide by 4 to get a per tire number.

AND....isn't there a plate or sticker somewhere with recommended pressures ?? You should be safe using those in most situations.

[Ivylog]

I add 5 psi to the table #s for various reasons so 80 front and 90 rear.

[rk911]

i have the same tires and my weights are similarvto yours. i run 85 all around.