hello everyone have a question I want to autocross my car more but it has 20' rims on it and the front tires are 30 series so there isn't much side wall on them if I were to get another spare and mount up two real tires onto the one I have and the one I might get would that be better I know it wouldn't be as good as buying track wheels and tires but I'm trying to get results cheaply and what size tires could I go with my rear tires are 285/30/20 thanks everyone

 

What width are your front wheels? A 245/35 or 255/35 would be a typical staggered front tire (on a 8.5 to 9" width) to go w/ that 285/30.

 

my 20 inch rims it's 245/30 what size could I squeeze onto spare 18' rims that would be close to same outside diameter of my rear wheels?

 

whats the width of the 18" wheels ?...you'll probably be limited by rim width in selecting tire sizes for 18s...typically they arent more than 8.5" in wichcase you'll max out at 255

 

A 245/45/18 would be very similar in diameter to that 285/30/20
This calculator will help
https://www.myg37.com/forums/tire_rim_calculator.php

 

For your help