my car currently has three 235/45/17 and one 225/45/17 tire. so i'm guessing 235/45/17 is the right size but i'd like to be sure before i ordered tires.

unfortunately this is the only picture i have of the car, the rims are genuine BMW/BBS wheels, so does anyone know how wide they are and what size tires to get?
http://i31.tinypic.com/vgn7kg.jpg

those look like style 5 17's from an E39. do you have hub rings on the car? If so, id bet they are 17 x 8. I have 225/45 on my car, and the look is just right. You can run a 235 on the car, but you wont notice a performance increase with it, but you may notice a price increase.

-Jeff

hub rings??

according to tirerack for 8" rims the recommended is 235.
the 225s have 1/32" more tread, but the 235s have 8 less rotations per mile and they both weigh 21lbs. so i guess they kinda even out.

the 235s are only $3 more per tire. i kinda wanna do 225 on the front and 235 on the rear cause i'm indecisive and that way i can just be in the middle. but i hate understeer...someone help me decide.

if you take the center cap off, both size dimensions will be stamped on there...i'd double check that just to make sure (not that jeff isn't trustworthy.)

8Jx17H2 is what it says so i'm guessing it is 8x17, but what do the J and H2 stand for?

J is a designation for the bead seat profile.

235 x 45 x 17 in the front, 255 or 245 x 40 x 17 in the rear

use tinypic.com for hosting. that pic is too small.

Second try on that pic.

I know a lot of forum content filters specifically block tinypic and tinyurl. Flickr is the best photo host.