tire pressure on tow vehicle

hawkeye-08 wrote:
To carry the load the tire is rated for, you need the max psi on the sidewall. If you are carrying less than that, adjust accordingly. P-metric tires are often filled to recommended pressure on door jamb sticker, but that is not for the max load, that is for comfort.

Partly true...The pressure listed on the door jamb sticker is not for "comfort", that is the pressure required to support the load of the vehicle and its contents loaded to the full GVWR.

If the tire says 44 psi max on the sidewall, the tire will carry the max load listed on the tire's sidewall at that pressure. If the door jamb sticker says 35 psi, then that's all that is required to carry the max rated load of the vehicle. Now whether you are over your max rated load with the trailer is another question....

Many report better stability via the stiffer tires running at the tire's max rather than the the mfrs inflation on the door jamb.

FWIW, this was exactly the issue with Ford and Firestone on the Explorers years ago...Ford rated the Explorer with a low GVWR and spec'd tire pressure to match. The roominess of the SUV had folks unknowingly overloading their Explorers and causing blowouts which were blamed on the tires since nobody actually weighed their SUVs packed full of stuff. Firestone's response was that the tires should have been inflated to the max sidewall pressure, not the lower number on the door jamb.

So (these numbers are just to illustrate) if the tire's sidewall says it can carry a max load of 2000 lbs at max pressure of 44 psi, but the vehicle manufacturer specs a rear axle rating (RAWR) of 3000 lbs, each tire only needs to carry 1500 lbs when the axle is at max capacity. So the vehicle mfr can spec a pressure of say 35 psi on the door jamb, since the tire will safely carry 1500 lbs at 35 psi.

Increasing the tire pressure from the vehicle's specified 35 psi to the max on teh sidewall will increase the carrying capacity of the tires but NOT the vehicle.