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Discussion Starter #1
I am new to the SLK World... literally just bought my car yesterday!!

I was hoping someone could help me with wheel/tire sizes.

I would like to get a set of 18" wheels and tires. But this is the first car I have had that has different size tires on the front 205/50-16 and back 225/50-16.

Could someone tell me what the comparable 18" tire sizes would be. As far as I can tell the WHEEL size is the same front to back, 18"x8".

Any advice appreciated.
 

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Administrator 2009 SLK 55 AMG/Founding member 2006
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As far as I can tell the WHEEL size is the same front to back, 18"x8"

18 inch front n back but not the same tires size

usually 225 in the front and 245 in the rear
 

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Administrator 2009 SLK 55 AMG/Founding member 2006
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Premium Member 2001 SLK320/2000 SLK230
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You want front and rear to be within 3% of the same diameter and do not exceed 26". Mercedes wheels should have the proper offset: 37 front and 30 rear.

Can model sizes at Custom rims, wheel tire packages

225x40x18 is about the same diameter as a 255x35x18 (25.1" vs 25") but the rear offset is critical.
 

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Registered 05 SLK55 & 06 Kleemann 55K S8
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Padgett nailed it. I have 18x8.5 in the front and 18x9.5 in the rear. I wouldn't go any wider for wheel size. I have 235/40 in the front and 255/35 in the rear.
 

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Discussion Starter #8
Ok this is really good information, thank you so much!!!

One more clarification: Related to offset....

I am looking at these wheels I like which have a offset of 40, which means that the rear would stick out an extra 10mm and the front would stick out an extra 3mm, correct?
How much give is there in this offset?
If I understand correctly, I would need to find wheels that come in 2 different configurations/offsets.
What would happen if I put offset 40 all around?
What about 35mm on back and 40mm on front?

Thanks for you're help answering my questions.
 

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Premium Member 2001 SLK320/2000 SLK230
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Have it a bit backwards, as offset goes up, the tire goes in.

Suspension design has always been a bit of an art form, did a lot of modelling when an IBM 370 was my PC, particularly over one gee transients. Must have worked since have a lot of trophies. Pretty sure was the first to model "unladen understeer" and the positive effects of turnin/late braking.

Personally think any profile under a 50 belongs on a racing suspension designed for it. Have no desire on a street car to tell if a cigarette butt in the road was plain or filter.
 

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Registered 05 SLK55 & 06 Kleemann 55K S8
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The nice thing about buying wheels with too big of offset is that you can put a hubcentric spacer behind it and get the wheel exactly where you want! The fronts should be find and you might need 5mm spacers in the back.
 

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Discussion Starter #11
The nice thing about buying wheels with too big of offset is that you can put a hubcentric spacer behind it and get the wheel exactly where you want! The fronts should be find and you might need 5mm spacers in the back.
So if I did get these wheels with a 40 offset all around, wouldn't I get a 10mm spacer for the back? And then just leave it as is in the front, which would be 3mm to the inside.

Is there anything "bad" about wheel spacers?

Thanks again all... clearly a newbie when it comes to wheels. It is an art form!
 

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Premium Member 2001 SLK320/2000 SLK230
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At this point we are really discussing "Kentucky windage" e.g. making a SWAG. If you have the stock wheels on your car now, I'd just try mounting the new ones and see if they rub.

If just a little (e.g. can still turn the wheel but scrapes) then you may just need 3mm spacers. These may be enough and in general the wheel can still register on the hub. 10mm or 1/2" is probably going to need to be machined to maintain the hub and those get expensive.

Or may not be an issue, only one way to tell. Can say that a 19x9x20 is too far out on a R170 for a 255 to clear the lip.
 

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Premium Member 2012 SLK55 AMG
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Ok this is really good information, thank you so much!!!

One more clarification: Related to offset....

I am looking at these wheels I like which have a offset of 40, which means that the rear would stick out an extra 10mm and the front would stick out an extra 3mm, correct?
How much give is there in this offset?
If I understand correctly, I would need to find wheels that come in 2 different configurations/offsets.
What would happen if I put offset 40 all around?
What about 35mm on back and 40mm on front?

Thanks for you're help answering my questions.
I always use this website when I’m looking for new wheel and tyre combinations. The illustrations will help you visualise the effects of different rim widths, offsets and tyre sizes. It will also calculate the speedo error based on the new overall diameter.

Www.willtheyfit.com
 

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Discussion Starter #16
Thanks all for your help and advice.

After obsessing about this forever, I finally landed on these wheels and tires. They came out AWESOME! in my opinion.

Front: 18 x 8.5" with 35 offset & 225 40-18 tires
Rear: 18 x 9.5" with 32 offset & 255 35-18 tires

The overall diameter difference on both were less than 1% difference which was perfect. And my mpg was only affected by about 1.5 which isn't too bad.

See attached before and after.

Thank again!
 

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Premium Member 2012 SLK55 AMG
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3,309 Posts
Z

That’s strange as I tried 8.5 x 18 et35 on the front and they hit the suspension strut (although mine is a 2005 350)
The first set I tried were 8 x 18 et40 and they hit the calipers.
Did you fit spacers to the front or did they just bolt straight on?
 

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Discussion Starter #19
That’s strange as I tried 8.5 x 18 et35 on the front and they hit the suspension strut (although mine is a 2005 350)
The first set I tried were 8 x 18 et40 and they hit the calipers.
Did you fit spacers to the front or did they just bolt straight on?
No spacers. They bolted right on.
I dry fit the wheels to make sure they had the clearance they needed, and both rims came out nice and even front to back. It was perfect.... I couldn't be happier with the fitment. I did report the offset backwards in my post however.

I have been trying to figure out how to edit that post...don't see any way to do that.
 

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Administrator 2009 SLK 55 AMG/Founding member 2006
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No spacers. They bolted right on.
I dry fit the wheels to make sure they had the clearance they needed, and both rims came out nice and even front to back. It was perfect.... I couldn't be happier with the fitment. I did report the offset backwards in my post however.

I have been trying to figure out how to edit that post...don't see any way to do that.
you did not read my welcome post then

you have 9 posts

you need 15 posts to edit and message other members

If you wish to become PM (Private Message) capable or to ‘edit’, you need 15 posts. To get those 15 posts quickly, just go to the ‘New members introduce yourself here’ section and welcome enough new members to obtain your needed posts to PM/edit. You can always pm a moderator.
 
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