I've spent a lot of time in consternation about what to do with a set of SL R230 AMG wheels I picked up a while back for my R170 SLK. While the wheels are the same in appearance as the stock sport wheels on the SLK, they are one size larger. I even went as far as to buy a set of cheapo tires to fit to them so I could test fit them to the car. But I am having problems with the front, more cosmetic than anything but it is driving me nuts...
The stock wheels are 17x7.5 et37 and 17 x8.5 ET 34 rear, the SL wheels are 18 x 8.5 ET 30 front and 19x9.5 ET 33 rear, I bought a set of cheap 225/40/18 for the front and 255/35/18 for the rear and that is where my dissatisfaction began.
Both tires on these wheels are a stretch, both literally and figuratively, but the front is obviously way to narrow for such a wheel and looks down right wrong on the car. For the rear, I think I can fit 265's on these wheels and currently plan on doing so once I get my suspension sorted.
After more than a week of deliberation, I have almost decided to leave the stock 17x7.5's on the front and have 17/18 staggered on the car (I've been driving around like this for a week and a half with no issues). Below is how the car sits now with 18's rear, 17's front..
The question I have for those who have more experience with tires than I do; do different tire manufacturers tires of the same size differ in width from model to model, or are those who have used 225/40/18 on 18 x 8.5 wheel just lived with the stretched tire on their fronts? I have read tons of post with others who have put 18 x 8.5 and 225/40's on their R170 and other cars but to me this just doesn't look wright on these wheels.....
Safety issues aside, the look in this scenario (narrower tire on wider wheel) just looks wrong to me thus I'm trying to determine if a different brand tire might fill out the wider wheel better. I would think a 225 is a 225, but have been wrong before... Those new Puma racing shoes I bought for example... Euro shoe sizes aren't same as US.
Based on this chart, it doesn't appear that anyone has ever used anything wider than a 225 on an R170 chassis... Mercedes-Benz Fitting Chart and Wheel Fitment Guide | Alloy Wheels Direct
All indications are that we can not get any wider than a 225 on the front of our cars, but with these wheels I obviously need more tire.
While unrelated and more or less fruitless, I even test fitted the one remaining stock rear wheel to my car and it appears to fit and looks a little better than the 225/17, but since I only have one good 17x8.5 I couldn't test drive with it and again haven't heard of anyone working wider than a 225 on the front of an R170 so worry about rubbing
So what if anything will fit? Could I get wider with a different suspension setup? Lowering the car doesn't make sense to get them to fit...