You're not looking hard enough. There are plenty of lightweight 18s.

 

What are you talking about? If you go with TALLER wheels then you won't need WIDER fenders.

If you go with WIDER wheels then you might need WIDER fenders. I run 18x8.5 with +30mm offset in the summer with no fender work done at all. No rubbing, no issues. People run 9 inch wide rims with no problems at all as well.


As far as the lightweight wheels being only in 15 inch sizes, that's because they're physically made with less metal. Look at some Volks, Advans, or BBS's if you want lightweight and strong wheel in 18 inch sizes.

 

I just bought some new RE30's that are 18x9 (only 17lbs each) and im putting a 265/35/18 tire that will be fine with my offset. Very much of it depends on your wheel offset and what size/type of tire you go with. With my setup by just rolling the rear fenders you can even go up to a 275 tire.

Give aspec a call they actually have Mackin's evo x test fitting wheels. These guys have done TONS of tire fitments for our car.

 

yeah i just started the search...
good info.