Does anyone know the correct daily running pressure for a 37x12.50R20 brand renegade R7 M/T? I have searched and searched. I just had these installed and they seem to be over-pressurized.
thanks

 

chalk test
Go to some nice , smooth, black asphalt.
Run a thick line of chalk over each tire. Drive about 1-2 full truck lengths, then get out and inspect the tires. If the chalk is wearing more in the center, too much pressure. If it's wearing more on the outsides, too little pressure.

 

Chalk test will be accurate. But the number suggested on the door jamb is a good start. Most LT tires are mounted on heavier 3/4 and 1 ton trucks and NEED 50PSI or more in those heavier trucks. But in lighter 1/2 tons need less air pressure. Most tire stores over inflate them when mounting them for 1/2 tons. Mine were at 50 PSI when I left the tire store with 85 PSI listed as max. I experimented with different pressures and settled on just under 40 PSI.

 

Chalk test is worthless with heavy duty truck tires. Best to use the PSI shown on the door jamb and then after a few thousand miles check the wear pattern on the tires and make adjustments. I have tried using the tire manufacturers' load charts but the indicated air pressure was too low which was obvious with the resulting wear pattern.

 

I’ve found the right number is often somewhere between the number on your door jamb and the max pressure number on the tire sidewall.

I typically pick something in the middle and then modify from there based on how the truck handles and if I can tell if there’s uneven wear after several thousand miles. I’ve had different tires vary as much as 10 psi too.