Rear tire PSI
 

On a set of 275s for street use. What PSI is best for traction?

Probably 30 or so?

Do this.

Fill the tires with 34psi. Take a piece of chalk and draw a line accross the tread. Drive around on a dry day a little bit, and then check the line. If the center is worn out, drop the psi. If the sides are worn out, raise it a little until you get even chalk line wear. From that point, subtract a few psi or so for street traction but not too much.

thats a good idea. i run about 30 in my 295's

you should be asking for the best pressure for sitting in a garage.

Optimal pressure depends on a lot more than your tire size. Billy's advice logically seems like the best and seems to be the concensus on other sites. This is what I plan on doing on the 71 when I get to that point. With wide tires and different weight/stance than the factory, what the manufacturer says is no longer going to be correct.