mike-s wrote:
P275/55*20 is good for 2216 lbs per tire at 29 psi. So, about 4500 lb on the rear axle @30 psi. What's the RAWR? If less than about 4500 lbs, more pressure won't get you more capacity. And, I'll bet it's right around 4500 lbs - manufacturers spec tires and pressures to support the ratings they give. If the sidewall max pressure allows it, I might run an extra 5 psi when towing, but not more for treadlife.
I believe a 117 tire is rated @ 2833 lbs. Derate that 9% for p tires and you get 2578 lbs per tire.
And constant working load usually another 20% per the manufacturer's. So that equates 2062 lbs per tire.
Whats your axle rate? 4000 lbs? Ahhhh.. Yup
To the OP. I would run at 40psi. Heat from the weight will be the issue. Higher pressure less heat.
Ive never ran the door tags psi in any vehicle I have ever owned. Always higher.
Now just talking here...
And from what I know a tires speed rating is calculated at max side wall pressure because of heat. So a v rating ( your tire) is 149mph. At that speed you would want 50 psi in the tires.
overinflated tires are safer than underinflated ones.
