tire size? can I get some opinions.

[hotrod363765]

Hello, My son and are are about to order up some goodies from porterbbuilt and start the transformation of his 1970 C-10. Going with extreme dropmember front and rear so it can lay down, I'm thinking about American racing vn425 ( torque thrust ) in 18x8 front, 20x10 rear. I like a tire with some sidewall, so I'm thinking 245/45/18 and 275/45/20. fronts are 26.7 diameter, rears are 29.7 diameter..... is that too much difference in height? sidewall is 4.34 on front and 4.87 on rear. Lets hear from some experience, thanks, Jeff