Please indulge me as I am pretty dumb when it comes to this stuff. I am debating 18" wheels for my new E but the car is a daily rider. I live on Long Island and am often in the city. I have been told I will bend them like pretzels. Will only a certain size tire work with a particular wheel? i.e. the car currently has 245/45 17's. I noticed in tireracks ad that there are 245/45 18's. Will that only work with a certain wheel. I have heard that the recommended tire for the AMG wheel is 245/40. Is that significantly different. Also, will the 18's effect my speedo, or airmatic suspension in any way. Thanks.

18's will not be a problem on any road. 19's could bend easily depending on the wheel quality and also depending on your driving style. The new E can fit up to 20" wheels. Usually if the stock size is 245/45ZR17 and you want to go with 18" the second number drops by 5 and ofcourse the last number goes to 18, example: 245/40ZR18. You must keep the overall diameter of the tire in order for your speedo to be accurate. You increase the wheel diameter but you decrease the tire sidewall, therefore you stay within the same overall diameter of your original tire. Always go with what AMG says, and never buy wheels from your dealer.

Given that you drive into the city a lot, I'd personally stay with the 17's -- I have 17's mounted on my car (2000 VW Passat), and I've bubbled numerous sidewalls and one rim has a slight bend in it. Granted, the new E-class has slightly taller sidewalls as the OEM size, but I still wouldn't want to take that kind of chance.

If you want, email me and I'll send you an Excel file that I created to help calculate tire/wheel sizes.

ajchenmph@yahoo.com

The web site at Tirerack has a nice explaination of how to calculate diameters and tire sizes. If you keep the same diameter, the speedometer will be accurate.

18x8 wheels, front a rea would required a 245/40R18 tire on each wheel

A staggered setup would be
18x8 with 245/40R18 for the front
18x9 with a 275/35R18 for the rear

The sidewall height is calculated by taking the tire width in mm and multiplying it by the aspect ratio.

For example: 245 x 40%=98. Therefore the sidewall height is 98mm, approximately 3.9 inches.

Your stock tires are 245 x 45%=110.25. Therefore the sidewall height is 110.25mm, approximately 4.3 inches.

The difference is an approximate reduction of 0.5 inches overall or 0.25 inches of sidewall on each side of the wheel, if you can understand my explanation.

The ride may be a bit stiffer and bumps may become more noticable, but overall, this is not a huge increase in wheel size. Would be great for everyday.