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2000 clk 430
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I have upgraded my wheel to 18 with 18x9.5 in rear ..... I was looking for different tire size for rear. Which is best ..... 255/35 18 or 265/35 18???


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'01-E320 & 02-ST2
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I have upgraded my wheel to 18 with 18x9.5 in rear ..... I was looking for different tire size for rear. Which is best ..... 255/35 18 or 265/35 18???
That all depends. What tire size do you have in front?

That is key, because it is critical that you not vary too much from the front tire OD; otherwise you will cause malfunctions with various safety systems (ABS, ESP, BAS, etc.).
 

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2002 CL55 AMG, 1993 190E 2.3L, 2004 SLK320 Sport
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255/35/18's in the rear for a 18x9.5 rim
&
225/40/18's or 235/40/18's for the fronts if your wheel is 18x8.5
if your wheel is 18x8, stick with 225/40/18's...
Just giving you my opinion, these sizes have worked for me in the past on
my E55 and C43.
 

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In the front I have 225/40 18 x 8.5


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Thanks. 255/35-18 is an ideal match for that front tire size. However, if you want a little more rubber you are fine using 265/35-18 and that won't upset your car's electronics. Either of those sizes will fit your rear rim width as well.

Good luck.
 

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Which one would make the rear look pretty good??


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Most guys say bigger looks better. Others say that size doesn't matter, it's how you use what you have. ;) Of course having a little extra rubber on the road allows you to use more of it, true?

I would first focus on trying to match the tires you have on the front already, brand and model. It would suck to end up with a mismatch and some weird handling or noise issues. If both sizes are available in a comparably-matching tire, then I'd probably go with the 265/35-18.

Good luck.
 

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1998 CLK 320 Elegance Auto
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Most guys say bigger looks better. Others say that size doesn't matter, it's how you use what you have. ;) Of course having a little extra rubber on the road allows you to use more of it, true?
No, because contact patch is dictated by vehicle weight and tyre pressure, not by tyre size.

If the tyre is wider the contact patch is wider, if the tyre is narrower, the contact patch is narrower and longer.
 

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No, because contact patch is dictated by vehicle weight and tyre pressure, not by tyre size.

If the tyre is wider the contact patch is wider, if the tyre is narrower, the contact patch is narrower and longer.
You're getting a bit esoteric and I hope you are just being humorous.

If you really want to get that fine a point about it, we can do the calculus, but you're comparing a static theoretical contact patch to a dynamic one that is turning corners, with speed, load transfers, etc., which greatly affect the contact patch both in shape and in size. Heck, that's why they use bigger tires and staggered setups to begin with, otherwise we could just keep using balloon tires from a hundred years ago.

If you really want to have fun with this, study contact patches on motorcycles as the lean angle starts and increases. ;) That's what first got me interested in them.
 

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Yes it was humorous in regard to the common misconception that adding width is automatically good. I assumed your original comment was meant with some humour as well?
 
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