I was been unable to find any information on changing my A180CDI low-profile 215/45/17 wheels/tyres for higher-profile 185/65/15 ones, to improve the ride. My model has sports suspension and has a hard ride.
MB could not help (‘speak to a dealer’ – who would not comment).
So I went ahead anyway, and thought my experience might be useful.
I bought some standard 15” MB steel rims (the alloy wheel bolts are the correct length on this model) and put on 15” Uniroyal Rainexpert tyres, for a total cost of c. £210, only slightly more than replacing the original 17” tyres alone.
The result is a significantly more comfortable ride, on much cheaper tyres. It is still not as comfortable as my old Honda, but anyone wanting to do the same thing should be able to feel the difference. My insurance company has charged me an extra £10.00 p.a. for a change to the wheel specification.