Put 20" rims on any car.

If you like big rims, in the underground mode unlock a car that can get 20" rims, unlock the option of having 20's, after you got both of those things, trade in your car for the car that get's the 20"'s. Choose the rim then change your car for the one you use to have. Now you have 20" rims on your car. This can be done with any size rim, Say you dont like the small size of 16" rims but you like the style, you can get 18's in that style. You can get up two 2" bigger on any rim.

you can get as much as 4'' bigger of that rim because i have 20's on the miatia