[J-Rod]

So, there's a guy here who wants to trade his 19" csl style wheels for 18" stock bmw wheels. He's got them on a 335i right now. I asked offsets but he doesnt know. I have a friend who sells wheels and tires, and told me he had to "shave off couple of mm for his new set of wheels to fit. I told him this would probably compromise the strength/integrity of the wheel. He said his were not affected at all. I definitely am worried and hesitant to do this. More so since the streets here are crap.

Any opinions/experiences?