[Shomeyrwit]

I know there are trade offs but if your using a car almost exclusively for highway driving how do you determine what size tire will put you in the sweet spot for a given rpm torque and speed?

I have played with tire sizes a lot on a variety of cars and trucks and have always kept track of the mpg even if it didnt matter but never actually tried to do the math on when a tire (or gear ratio) is to tall.

Thanks in advance