tire sizes....i'm confused

[comrade1]

what size tire am i supposed to get? i am getting a set of 17x8.5 wheels but the guy said they need new tires. he used to have 225/45/17 on a e46. i checked tirerack and for my e36 they say 235/40/17. one of my friends said to get 205's and another said to get 245's.

what size should i get and why? thanks guys![???1]

 

[Big Daddy]

You can find the factory sizes on the inside of the driver's (left) door on a sticker. I believe the Tire Rack is correct. Some sizes are interchangable and or you can plus size. The biggest thing is keeping the overall diameter of the tire and wheel the same.

 

[kerph32]

what year and model do you have?

 

[mikev]

Ok heres how i think it works.

Tyre Size Guide

Identifying the right tyre size for your car is simple, looking at the tyres on your vehicle you will see the size embossed on the side of the tyre (as illustrated below)

So for your Wheels you have you will need the correct Width and Rim size. aspect ratio is the profile of your tire. the lower the profile the less flex you have and the more the car will stick to the road. but if the aspect is too low then going round corners could cause slapping. (Where all grip is lost instantly making it much harder to control) higher profile tires allow for a much more controlable and fun car but it wont be as fast. 225 width and either 40 or 45 AR, X17" is my choice. You also need to get the speed rating correct. 8.5" is just over 215mm so 205 would be too small and 245 way too big.