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Matt, Mechanical Engineer
Category: Mercedes
Satisfied Customers: 22913
Experience:  BEng hons Mech engineering, in auto industry 22 years
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I have just bought a 2008 Mercedes C220 Sport CDI. 1 owner,

Customer Question

I have just bought a 2008 Mercedes C220 Sport CDI. 1 owner, 42,000 miles, garaged and very clean. However when comparing the ride comfort with my 14 year old 5 series BMW the BMW is far smoother. The Mercedes shudders every time I go over a matchstick and the ride is not at all what I expected. Is there anything that can be done to the car to rectify this? Is there a Mercedes that does have a smooth ride? Should I sell this car and go back to BMW?
Submitted: 3 years ago.
Category: Mercedes
Expert:  Matt replied 3 years ago.


The first thing to do is check that the tyre pressures are correct to those stated in the manual , if this is OK then its also worth making sure that the suspension geometry is correct as if a camber or rear toe setting is out then this would make the car feel nervous,

I'd recommend taking the car to a place that does 4 wheel suspension alignment, most places use the back wheels as a datum and assume that they are perfectly straight and true. Often this is not the case and many modern cars are now adjustable at the rear as well as the front.

A 4 wheel alignment measures all four wheels independently and each is set -up without referring to each other and should only cost around £40.

If looks Ok then I'd consider fitting a taller profile tyre with a smaller diameter wheel, this will add some compliance to the ride and generally calm the quick responses. An alternative is to keep the current wheel and replace the tyres with some of a softer sidewall so removing some of the compliance in the system - Toyo's for example

This is especially true if you have run-flat tyres currently fitted

If you look on the tyre at the end of the number there's a letter, the number just before this letter denotes the load capacity and therefore sidewall stiffness.

ie 225/55 R16 91V its the 91 you're interested in try a tyre with a lower figure and you'll get a softer tyre, however bear in mind this will also soften the steering response

Its also worth checking that all the main suspension pivot points have been tightened with the car on its wheels not in the air as this can add a lot of friction to the suspension

Customer: replied 3 years ago.

Hello Matt, Thank you for your help.

At the moment the Mercedes has Continental tyres on the front size: 225/45 R17 94W and Pirelli on the rear:245/40 R17 91W.

My old BMW has Hankook tyres 225/55 R16 99W.

What do you think are the optimum tyre sizes that should go on the Mercedes to give me a smooth ride ?

I will get the alignments checked, but do you think it will make a big difference if I change the tyres and the wheels ? If so what size wheels would you recommend ?

Thanks, Alan

Expert:  Matt replied 3 years ago.
Hello Alan

presuming that you don't want to buy new wheels then I'd go for a 235/45R17R17 91 on the rear and a 215/50R17 91 on the front

if you can get a lower side wall number than 91's then go for it but in this size 91 is most common