Hi.....
ý am new in this form and sorry about my english because my mother language is now english....

I have 225 45 17 ZR micheling tires on my car(CLK200K) but my tires are not found in my country any more(ý guess they are not made anymore) so we buy different kind of michelin pilot series;
so the design is different on tires
fronts are new michelin pilot and they are y group....
backs are z group..

what are the disadvantages of having different types of tires?
does it cause any problems?

No problem as long as you have the same ones on one axle ( same tires front, same tires back ).

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2007 C 230 Sport.