I purchased a used 2005 Mazda 3 and the previous owner upgraded the rims from the 17'' to 18''. I love the way they look, but the tires rub the bottom inner part of the fender when I go over hard bumps. The tires are a bit wider profile but it seems that a stiffer rear suspension is needed.

Any recommendations?

 

its not the 17-18, it's probably the tire width... stock was 205 wide, and I think 53mm offset? If the rims offset is wrong, or if the tires are too wide - that's your main problem.

 

I put 18x8 vs factory 17x6.5, and lowered with coil springs from Tein on a mazda 3 05 and until I installed the camber kits was fine, IF you are not gonna change the rims the most thing they do and I did was take it to the paint shop and made them cut that lip so the tire can go up with no problem...