width

Today I was walking towards my car from the back and I noticed how thin my tires are :facepalm: ... and I am planning on getting a new set because they're almost done... What's the widest I can go in the back with 17" rims and 18" rims? I'm currently running 225 with 17's

I'm going to get dedicated rims and tires for the track. I'm in a 2003 330xi. All I've driven so far is a stock setup: 205/50/17. To be clear, I'm not going to race. I just want higher performance at the track (and maybe they'll get some street time too.) Question: how wide can I (should I)...