I have searched, but couldn't find a definitive answer to my question. I currently have 18x9.5 (ET39) wheels on my rear. They have 265/35/18 tires and there are no spacers required. I tried putting on a different brand having the same size, but an offset of 35 on. The shop showed me how they were too close to the suspension (strut housing). I was thinking that 39 - 35 would be equal to a 4 mm difference. However, it seems that if I were to add a spacer, it would subtract from my offset. What is the best way to get the new wheel to fit?

 

The offset questions above stemmed from me purchasing the 817 AMG wheels from sonictuning. Ray was pretty cool and helpful, and the wheels arrived quicker than expected. The front wheels had an offset of 32, replacing my offset of 35. I ended up putting on a smaller spacer up front to clear caliper. It was very close and looked as if it may end up hitting. The rear wheels have an offset of 35. Ray suggested that I wouldn't need a spacer, but the techs at Goodyear said that the wheel was too close to the struts. I then went to a shop in Philly and purchased a 12mm hub centric spacer. After going one block, I noticed a clicking noise and took the car back. The owner shaved down the bolts and the clicking went away. Due to the 12 mm spacer, my 265/35/18s were sticking out past my fender. They rubbed like crazy on the slightest of bumps and turns. The shop owner shaved down some edges on my already rolled fenders due to some rubber being cut. When I got home my tires had little cuts in them. Being bothered by Ray suggesting that I wouldn't need spacers, I put my old rims (aftermarket) on to see how close they were to the strut housing. They also looked as if they would hit the strut housing but never did. I then removed the spacers from my new back wheels and took it for a test drive. I heard very loud clicking before I got 5 feet. After a wasted trip to the dealer, I found conical stock length bolts at Pep Boys. Clicking continued. I had 2mm ( I guessed on the length) removed and the clicking got quieter. It now sounded as if the very tip of the bolts were making contact with emergency brake system. Tonight, I shaved 2-3 more threads off and no more clicking. I just got in from a 5 minute drive with the windows down and heard no clicking. Yes. Ray aka Sonictuning was correct. I am happy again. Sorry for my life story.

 

The O.E.M. wheels on a C32 are 7.5x17 ET37 and 8.5x17 ET34.

 

Here is the car with the wheels on.