Just acquired a 1998 CLK 230 and it needs new tyres. All four corners are 205/55/R16's but the tyre shopping sites say they should be different front to back (as do some posts on this site). Could anyone tell me how to find out what size is right for my car? The cruise control doesn't work which started me thinking about tyre sizes. The wheels are those horrible Elegance alloys. Many thanks in advance.