wheels,how big?

thanks for replies to my last post guys!
How big can i go with my wheels,ive got a set of 17s that will fit but i want to drop it by about 40mm so dont know how much hassle i am creating for myself,do i have to skim the arches or will they not fit at all,im a novice at modifying normaly i just restore,thanks again.

Danny.

15 is about as big as you want to fit 17 will give you problems and look  :roll: Plus loads of hassle getting them to fit .