Tire inflation question

[Al Fresco]

My 2011 Sunseeker (E350 super duty chassis) is equipped with Michelin LT225/75R16E tires. I recently had the motor home weighed fully-loaded for travel.

Combined front axle weight = 3,660 lb. (Front GAWR = 4,600 lb.)
Combined vehicle weight = 10,760 lb. (GVWR = 12,500 lb.)
Combined rear axle weight = 7,160 lb. (Rear GAWR = 8500 lb.)

I am not sure I am using the Michelin inflation chart (Google: "Michelin Inflation Charts for RV Usage Only") correctly to determine what the proper tire pressure should be. I assume that to estimate the single-tire value on the chart I should divide the combined axle weight by two. Thus, for the front tires, the value would be 1830 lb. (This, of course, assumes equal weight distribution on each tire.) If that is correct, then the recommended inflation pressure is about 46 psi. Using this same method, the recommended inflation pressure for the rear duals is about 51 psi.

As received from the dealer, all the tires are inflated to the maximum pressure listed on the tire of 80 psi. (The sticker on the door lists 65 psi.)

Are these tires seriously overinflated or do I just not understand how to use the Michelin inflation chart correctly?

[donn]

Inflate ALL tires to the maximum pressure as listed on the tires sidewall. It might make for a bit harsher ride, but your tires will thank you at the end of a hot day.

[Al Fresco]

Thanks for the expert advice. Looks like the dealer didn’t overinflate after all.

Is there any valid reason why Michelin (and whoever placed the sticker on the chassis door) recommends inflation pressures that are so much lower than the maximum listed on the sidewall?

[papap]

just bought a 2011 Solera and wondering the same thing now. Have not checked the pressure yet. But getting ready to make a 1700 mile trip and will check them before we leave for trip.

[donn]

Same as the sticker on every vehicle built. It is a compromise number to give a soft ride. It you look at the tire sidewall there is an inflation number that gives the load rating for that tire at that pressure.