Basically I wanted to see if anyone out there knows if I can run 255/30/20 for my front tires?

If so what do I need to run for the rears? I know the correct setup is 275/30/20 and 245/35/20 but I found a great deal on some 255/30/20 tires and would love to buy them. Please let me know what problems if any may occur. I am planning to lower my car also with springs. will that size rub/ do I need to roll fenders?

Thanks for any input from anyone.

 

There are 2 calculations to the equation
1. Total Radius
2. Total Width

If your on Sport suspension, I doubt you could do that.
I am running 245/40/19 so this is my equation

Sidewall height = 3.86 inches
Radius = 9.5 (19/2)
Total radius = 13.36 inches



Now for your setup
255/30/20
Sidewall height = 3
Wheel Radius = 10
Total radius = 13 inches

I could pass my pinky between my tire and my suspension base, a little more height and I was sure to touch.
As far as the total height, you are sure to be fine, with a non M fender and a sport suspension, you might very well RUB(not very sure though).