Well, when I first got my 215/40-16 tires, I had them mounted on my stock 16x6.5 rims. Although, the rims were definitely too narrow, they looked like they fit fine, better than the 225/50-16 tires I had on them before. Then I switched to some 16x7 rims and my handling improved dramatically, but the ride got noticably rougher.
This is how they looked on a Cougar lowered with Eibach's. As you can see, even with the shorter springs, there is still some unsightly fender gap, but it's not as bad as you might expect.
