What's the best tire/size combination for 2003 cl55 with 18" wheels? I recently installed the ventus 120 tires 275/40/18 rear and 245/45/18 front and the car started to drift and bounce on bumps, it also lost its tight grip. Any help guys?

those tire sizes seem right for 18" wheels. maybe try a different brand tire. i use falken and love them

Some of the obvious you need to check:
1. Air Pressure-Try as low as 32psi to solve you harsh ride. Not recommened for hi speeds.
2. Alignment of course. Take it to a reputable dealer/shop and don't go for the $100. job-MB's require some specialized equip such as by Bosh (ever notice those 4 little holes next to the wheel lug nuts? -that's for the Bosh Alignment equip)
3. May wish to check out the airmatics-Take to dealer with a compliant for a free check out.
4. Wheel Rim: Out of round rim or bent rims will do it. A wheel balance will tell the condition of the rims.
5. Tire Brand/Type: Check out Tirerack.com Read up on the particulars of tires as well as consumer feed back and ratings. A soft rubber with a rating of 220 is common on these cars for performance, handling and comfort. As with all brands and type of tires, some are good and some are bad and it varys for each car model.

I just put Michelon PS2's on front and rears. Very expensive tires especially for the larger sizes and hi speed ratings. It was a noticable difference in the handling and worth the xtra bucks.

Just my $.02

THANKS FOR THE INFO. Do you think the 275/40/18 rear is the right size with the same offsets or should I install 275/35/18 instead?

Tigerwild,

I think Mr Berman did a pretty good job in filling you in on all possible alternatives for a better ride. You don't want to go to a lower profile tire as a 35 series if you are complaining about the ride with what you have now. Maybe you should be thinking of a even taller series of tire ?
I run a 30 series in a 20" with the Michelins that Berman was talking about. I love the look and really think the ride is pretty good. Its a give and take or good with the bad situation. This is something that you are going to have to weigh out for yourself.....

Do you think if I keep the current series 275/40/18 my suspension will bottom out or will go bad?

I don't know if its you or the car.....but, something or somebody has a problem.....................

If you don't know the answer, I suggest you mind your own business and stop being an a....hole.

Huh ? Now I am A..hole for trying to give you help !!!! Your question was really on the verge of being really stupid, I just figured you were being a smart a..! Good with luck with YOUR problem.

I appreciate your help, but it could've been more constructive if you were not sarcastic. The car was aligned and wheel balanced but still drifts all over the place, I'm not sure what that's called since you are the expert!!