Thor Forums

[Chance]

Originally Posted by Fid

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However, I have noticed that the plaque on the driver side inside wall lists the pressure as 90 psi.

I am assuming the Thor recommendation on the plaque is a general recommendation. Am I right to follow Michelin's recommendation or should I be running 90 psi?

I wouldn't quite call it a "general recommendation". I don't think they have option to specify any lower pressure.

Manufacturers must specify required tire pressure to meet the chassis' Gross Vehicle Weight Rating (GVWR), including the front and rear axle ratings used to obtain that GVWR.

In your case I believe the motorhome is probably built on a 22,000-pound F-53 Ford chassis, which has 8,000-pound front and 15,000-pound rear axle ratings. Standard tires are 22.5-inch while 19.5-inch are optional.

With standard 22.5-inch tires, it takes 90 PSI to carry the maximum axle loads safely, which is why Ford and Thor include it in specs.