Tire Size Recommendations
 

Can someone help me with some rear tire size suggestions for a stock body, stock suspension is350? The spec on the wheels are 18x9.5, offset 40. I'm thinking of 255/40/18. I just want it to fit right, no stretching or any fender mods. Thx.

265/35/18.

^That, or 265/30/18s if you have a 35 series up front already.

Up front, I'm running 235/40 on 18x8.0, so 255/40 would not work?

Yes it would work; however, it's a slight stretch and a 35 series sidewall would make the fronts and rears "match" in sidewall height.