2nd opinion on tire pressure for peace of mind

[Dave_H]

I have Michelin 275/80R 22.5 XZA3+ Green X tires on the front axle and Michelin 275/70R 22.5 XZA2 Energy Green X on rear duals. I had been running 100 psi in the front and 95 psi in the rear duals until I could get the coach weighed. I recently had all 4 corners weighed while fully loaded and front left is 4900 lbs, front right is 5090 lbs. Rear right is 8860 lbs and rear left 8220 lbs. According to Michelin's tire chart (shown below) it appears I can run as low as 75 psi in the front and 85 psi in the rear and still have plenty of room for additional weight. This just seems a bit low to me and thus the need for a second opinion. I reduces pressure to 80 psi in the front and 85 psi in the rear duals and was totally surprised at how much overall ride comfort and handling improved. Am I good to go at these pressures.

[paddler1954]

I think I'd run 85 lbs all the way around. That would give you some spare capacity on the front and rear and should still give you the improved ride. Plus it would be real easy to remember, 85 in all tires.

[96 Wideglide]

Better check your math. 75psi is too low for your front axle!

[Ivylog]

I like to add 5 to the chart so 85 everywhere.

[Dave_H]

Originally Posted by 96 Wideglide

Better check your math. 75psi is too low for your front axle!

The chart shows 9830 lbs for a single at 75 psi and the heaviest side in the front is 5090 lbs. I agree 75 seems low though, i think I would feel more comfortable at 85 psi.

[96 Wideglide]

The weight you are reading on the chart is for that entire axle.

Your front axle weighs 9,990 lbs. 75 psi in your front tires would only be good for 9,830 lbs .

[Dave_H]

Originally Posted by 96 Wideglide

The weight you are reading on the chart is for that entire axle.

Your front axle weighs 9,990 lbs. 75 psi in your front tires would only be good for 9,830 lbs .

This is what I was uncertain about. This is from Michelin's tire pressure chart:
Load and Inflation Table Terminology
SINGLE means an axle with one tire mounted on each end.
DUAL means an axle with two tires mounted on each end.
The loads indicated represent the total weight of an axle end in an RV application.
Axles & Tire Pressure
Michelin displays tire loads per axle end in the load and inflation tables. We recommend weighing each axle end separately and using the heaviest end weight to determine the axle's cold inflation tire pressure. For control of your RV, make sure tire pressures are the same across an axle, while NEVER exceeding the maximum air pressure limit stamped on the wheels.

I interpreted this as a single tire at each axle end weight and what recommended pressure would be for that individual tire, not total axle weight??

[richard5933]

It's got to be calculating the per axle weight. There's just no way possible for that tire to have a weight rating of over 9000 pounds on one tire at 75 pounds. Just not possible.

[96 Wideglide]

Hopefully this link will work. Scroll down to the 22" tires.

https://www.goodyearrvtires.com/pdfs/rv_inflation.pdf

Notice the numbers on this Goodyear RV tire chart is about half what your Michelin chart shows. This chart is for weight per end.

[wildtoad]

Just for grins, how does the computed pressures compare to the placard in the coach?

[Dave_H]

Originally Posted by wildtoad

Just for grins, how does the computed pressures compare to the placard in the coach?

Placard in coach shows front GAWR of 12,000 lbs 120 psi max cold
rear GAWR of 19,000 lbs 120 psi

[96 Wideglide]

What does the placard list as the original tire sizes?

[Dave_H]

Originally Posted by 96 Wideglide

What does the placard list as the original tire sizes?

275/70R 22.5 Load Rate H on both front and back. Previous owner put 275/80R 22.5 Load Rate H on front steer. Rears are load rate J.

[lllkrob]

That Michelin chart is for TOTAL axle weight NOT corner weight. Based on your information and allowing for a 10% "safety" increase in your axle weights you should be running 90 psi in all tires.