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-------------BELOW IS THE MANUFACTURERS SPECSPer the Michelin website Max Load Per Tire Single 5205/110 lbs/psiMax Load Per Tire Dual 4805/110 lbs/psiLoads per Axle End PSI SINGLE,lbs DUAL,lbs75psi 4070 741080psi 4300 772085psi 4440 808090psi 4620 841095psi 4805 8820 100psi 4975 9050105psi 5150 9370110psi 5205 9610------------------I had my coach weighed at a truck stop with a full load during my trip two weeks ago. This is the resultsSteer Axle : 8020 lbRear Axle: 15840 lbQuestions: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= 7920Those 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 37tbAny feedback would be great, thanks.

You are figuring correctly. Each axle has two ends, so you divide the axle weight by two (and maybe add a little bit of a fudge factor since it's unlikely that the weight is perfectly balanced left to right). Something like 80 psi for the fronts and 85-90 psi for the rears would seem about right.The tires can safely be used on vehicles a good bit heavier than your motorhome. That's not at all a bad situation to be in.

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

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

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

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

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

DrewE
Explorer II
Aug 13, 2018
You are figuring correctly. Each axle has two ends, so you divide the axle weight by two (and maybe add a little bit of a fudge factor since it's unlikely that the weight is perfectly balanced left to right). Something like 80 psi for the fronts and 85-90 psi for the rears would seem about right.

The tires can safely be used on vehicles a good bit heavier than your motorhome. That's not at all a bad situation to be in.
rk911
Explorer
Aug 13, 2018
i have the same tires and my weights are similarvto yours. i run 85 all around.
Ivylog
Explorer III
Aug 13, 2018
I add 5 psi to the table #s for various reasons so 80 front and 90 rear.
Sam_Spade
Explorer
Aug 13, 2018
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.
MountainAir05
Explorer II
Aug 13, 2018
Should not the 15840 be divided by 4 for the number of tires on the rear.
STBRetired
Explorer
Aug 13, 2018
Nope. Divide by 2 and then compare to weights in "Dual" column.
DrewE
Explorer II
Aug 13, 2018
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.
Sam_Spade
Explorer
Aug 13, 2018
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.
mccsix
Explorer
Aug 13, 2018
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.
Executive45
Explorer III
Aug 13, 2018
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