what size wheel can i go up on my 89 325 4dr and what would i have to
Ya your going to piss people off if you post to many things like this. go to http://www.bimmerwerkz.com/ you will be able to find all the info you want.
I got 15" rims from Tire Rack for my 325i convertible with a 25mm offset. Then put on 225/50/15 all-weather performance tires and and had them siped - it handles great with no rub. The tread is 9" wide and the tire diameter is essentially identical, so the speedo is still correct. If you have big folks in the back and hit a big bump fast, it would probably rub in back. The front tires have tons of clearance.
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