Hey everyone,
Maybe someone can help me by giving me some specs or advice. Ok, i have a 79 Ranchero with a 302 that ive put a lot of money into for power. In the front i have BFGoodrich Radial T/A's P225/60-15. I want some bigger tires in the back, but not huge. I have two choices, but i don't know which would be better. First of all, i have Summit's detroit locker in the back (disengages on turns) with 3.50 gears. Now the two choices i have are P245/60-15 or the P255/60-15. Now either way the diameter will be bigger and will make my truck tilt (its already stock like that, so im fine with it, i kinda like it) so that perspective doesnt matter. I was looking at the specs on the site, and the main difference other than diameter is in the Revolutions per mile and the max load. The 245 is 782 r.p.mile and the max load is 1753@35 psi, while the 255 is 768 r.p.mile and the max load is 1885@35 psi. Now since im looking for performance, i would want wider tires, but since its only 10 mm difference, it really doesnt matter. Im not sure though if the rev. per mile is suppose to be more or less (or close to the front which in this case is 813). If anyone can help me on this, i would appreciate it very much! Im not the greatest when it comes to tires. Thanks everyone!
Danny

 

The revs/mile are directly related to the tire's height (actually the circumference). The bigger around, the less times they need to revolve to go a mile. The difference between the 245 and 255 is minimal, so unless there is a considerable cost difference I'd go with the 255's. I wouldn't worry about the load rating, who uses a Ranchero to haul heavy stuff anyway. My Grandpa had a '77 GT and I think the heaviest thing he ever carried was a few bags of grass clippings to the dump every weekend. I really liked that truck.