I have a 2001 f-150 supercrew the stock wheels that i run in the winter have the stock 255/70R16 tires. I have a set of wheels off of a 99 lightning that i run in the summer with 295/45ZR18 tires. Does anyone know what size 18's would be the same diamater as the 255/16's. I don't want or need to keep runing the 295/45's. $$$$$$$$$$$$$$$$ & i don't need that kind of performance. I throws the spedo off as well.

 

here is a site that gives an equation to help find the diamater.
http://www.geocities.com/MotorCity/2...s/tirediam.htm