wheel Q's
 

with our wheels being 16" 7.5 " & 50 mm offset - not sure how much clearance that gives us - obviously enough

would 17" x 8" & 40mm offset fit or would they likely to rub or cause problems?

and finally, why are rims measured in both metric and imperial?

Re: wheel Q's
 

Our stock wheels are +55mm offset.

17x8, +40 might work, but would be very tight. My BBS wheels are 17x8, +53 and leave a lot of space. I could run at least a 5mm spacer, probably an 8mm one if I wanted, but any more than that I wouldn't be too sure about. I think +45 is as far as I would go on an 8" wide wheel.