so, i have some wolfrace 15" alloys with 195/45/15 and it was rubbing on the rear as i have flat arches (im guessing this is why). so i took the angle grinder to the arch and its not rubbing no more 
if i continue to lower the front 40mm and go to a 195/50/15 (more common tyre size) is it likely to rub again ?..
if i continue to lower the front 40mm and go to a 195/50/15 (more common tyre size) is it likely to rub again ?..