Tire and wheel help

Here is your problem. With 20" rears, you are going to have to get much bigger tires. I look through a few DRs for the right size, and the closest thing I found was a set of 305/35-20s. They are over 28" tall. That is not even mentioning the fact that the 20x10" wheel is going to weigh about the same as a small moon.

A 305/35 doesnt leave a lot of sidewall, so regardless, it is going to be stiff and lost a lot of bite vs....say a 17" with similar overall height. I am going to go out on a limb here and ask....since you say stock ride height, you still have the stock suspension? Any other mods?

If the answers are stock suspension and near stock engine.....you will run WAY slower with 20" DRs than you would on 17" street tires.

I'd axe the 20's. Too big for these cars and kills performance from every aspect as mentioned by vertigasen.

You won't like the price of tires either, and they'll probably be more expensive for the 19's.