Tire Inflation

[Mark S]

I recently switched my Goodyear P rated tires to Michelin Defender LT 275-65 /18 tires on my 2015 F150.

I called Michelin to determine the correct inflation on the tires for my application. I was told that for unloaded / everyday driving I should run 55 psi which will carry 2,661 pounds per tire and that at 60 psi it will carry 2,825 and at 65 psi it will carry 3,000 pounds per tire.

So here is my questions: if my truck weighs about 5,000 pounds and I add about 1,500 pounds for tongue weight and stuff in the bed the total truck weight will be about 6,500 pounds, give or take. If at 55 psi the tires will carry 2,660 per tire, or a total of 10,640 pounds (2,660 x 4) which is about 4,000 pounds more than the total weight of vehicle, tongue weight and contents, do I need to increase the tire inflation?

And since at 55 psi the tires will carry about 5,000 pounds more than the actual weight of the unloaded vehicle, can I lower the tire pressure when not carrying a load?

The Michelin man says yes, that for every increase in weight I need to increase the psi and the charts did not show any weight limits below the 55 psi. This seems like overkill to me and was looking for other informed decisions.

Thanks, Mark

[clr]

There is a minimum air pressure number on a tire that you are never to go below even if the load on the vehicle will allow it. I would go the Michelin tire site and look up your tire and secure the inflation chart for you exact tire. Also you should really have your RV and TV weighted to make sure of your weights before you decide upon the air pressure to run the tires. It appears the you have a TT so with a WDH some of that tong weight will transfer to your front axle. So without hard numbers it would only be SWAG. But error on the side of higher air pressure until you get the hard data.