My 2006 MB CLK 350 came with different size summer tires on front and rear, with the rear slightly larger than the front. I want to replace with better gripping all seasons. Will using the same size tires on all four wheels have any negative effects on handling, etc?
You should check with the dealer if the car came that way NEW.
Yes it will. For one thing, you will probably find that the wheels are different widths, even if they are the same diameter. I.e., the front wheels might be 7x17 and the rear 7.5x17. Using same size tires all around may make the car oversteer, that is easy for the rear end to “come around” on you.
225/45-17 and 245/40-17 is what tirerack.com lists for your vehicle in front and back, respectively.
While I can’t say if it’ll affect handling all thast much, others should be able to steer you in the right direction with the info I provided
“others should be able to steer you”…an unintended pun?
Car makers pull stuff like this to cover up a poor design. This was the only way they could get acceptable results on a skid pad and have Car & Driver give them the kind of rating they wanted…If skid-pad G-ratings are important to you, then you will have to stick with the mis-matched tire sizes. If you are willing to accept a small degradation in handling performance you could install a matched set of tires but you may have to buy a set of wheels to do it…(see Keith’s post above)…
According to Tire Guides, the front wheels on this vehicle are 7.5" wide, while the rears are 8.5" wide - just as Keith suggested.
Needless to say, using the same tire size front to rear is likely to result in a difference in the way the vehicle handles.
And to address Caddyman’s comment. I am not aware of any vehicle manufacturer who tried to address a shortcoming in their design by using a staggered fitment. Typically, these staggered fitments are on the sport versions of a vehicle model that comes with the same size front to rear on the standard version - and that is the case here.
The only times I have been aware that vehicle manufacturers have tried to fix shortcomings in their vehicle design using tires is: 1) Carefully specifying tire properties out of the norm, and 2) Using odd inflation pressures.
It’s unlikely you’ll get better grip from all season tires than you would from your current summer tires.
You could go to the Benz dealer, purchase two new 7.5" (front) rims, and buy a set of same size tires mounted on matching wheels…Before you do this, you should investigate if this may interfere with the vehicles traction control system which may be calibrated to the two different tire sizes…