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Registered 2009 SLK55 AMG
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53 Posts
Discussion Starter #1
Gents,

I am planning to swap my 18" rims by 17". Roads here in Brazil are blowing my tires too often, I am seeing my wheels split in half if I don't do something. Tires 225/45 and 245/40 will give extra meat and maintain same track diameter.


QUESTION
I did some measurements and it seems it fits, tight though with 1/2" clearance on the side o the calliper for front wheels.

Could some confirm the 2009 AMGs discs/calliper wont rub against the 17" rims?

Thanks!
Fred
 

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Registered 2014 SLK250
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1,000 Posts
I sympathise with the problem!
Both MB and Brembo specs say that minimum rim is 18". I have only ever seen 17" rims with the smaller 4 pot caliper.
The only way to be sure is see if you can borrow a Mercedes 17" rim and try fitting it. If you can clear half an inch is good, but sounds optimistic to me..!
 

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Premium Member 2004 SLK200K
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10,761 Posts
The ideal would be if the seller can let you know the interior measurement of the actual wheels you're interested in putting on your car ....
 

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Registered 2014 SLK250
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I believe the AMG package went back to 4 pot callipers after the facelift in 2007. Apparently the 6 pot calliper from 2005-2007 were too expensive.

Any information would be welcome. I am buy the rims below:
Jogo De Rodas 17 Mercedes C 250 5x112 C180 C200 Original7 - R$ 1.999,00 no MercadoLivre
So, are you saying that you have the smaller 4 pot calipers and not the larger ones? If so, yes, you may well have clearance, but as above ask the seller to measure the wheel dish.
 

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Premium Member 2009 SLK55 AMG
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My SLK350 originally came with the 4-pot "Sports Pack" brakes which are unpainted but otherwise identical versions of the AMG 4-pot fronts. The car also came with 17" AMG rims. Suffice it to say that that combo obviously fit.

Here's a pic of the original wheels+brakes, with the AMG 4-pots in front for reference.



The thing that could possibly make things *not* fit would be if the brake caliper is mounted differently, to accomodate a larger rotor for instance. When I switched out my brakes (when this picture was taken), I also upgraded my rotors to the AMG ones, *but* I also went to 18" rims at the same time...
 

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Registered 2014 SLK250
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1,000 Posts
He'd be ok if he has those calipers - the 4 pots, as they will not fit larger discs.

Interesting the 55s were fitted with 4 pots. I have never seen any. In the same vein, the R172 standard 55 front array is with single pot TRW calipers, but again I have never seen any.
 

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Premium Member 2009 SLK55 AMG
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Interesting the 55s were fitted with 4 pots.
If I recall correctly, all 55s between 2005 up until 2008 had the 6-pot "brembo big brake" type calipers. In 2008 they switched to 4-pot as shown in my picture (the AMG brakes I hold in my hand came from etyu's 2008 SLK55). The only R171s that still came with 6-pot from 2008 onwards are SLK55s equipped with the P030 Performance package.
 

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Registered 2014 SLK250
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Allegedly it is the same with the R172 - only the P30 has the Brembos. From what I can see though - all 55s must have the P30 option!
 

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Registered 2009 SLK55 AMG
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Discussion Starter #11
I took a picture of my calliper (Front-right) and I noted the part number: 20.7046-04

I am not too sure if I have a 4-pot front callipers, I only knew that the pre-2007 (or 2008 as stated by Durk) had larger ones. I am under the impression that my AMG, being 2009 would have something smaller.

And if I do have 4-pot in the front, not sure if the 17" rims would still fit! I purchased the wheel, but didn't get them sent until I know they are they will fit.
 

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Premium Member 2009 SLK55 AMG
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I took a picture of my calliper (Front-right) and I noted the part number: 20.7046-04
Those are the 4-pots. Unless they are somehow mounted further from the hub center compared to my 350, you should be fine with those and 17" rims.
 

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Registered 2014 SLK250
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Agree - they are the smaller ones and will go under 17" rims.

There is another way to verify this if you want - how much clearance is there now between the outer edge of the caliper and the inner rim of your 18"s? The 17" rims are only going to close this clearance up by half an inch…maybe a fraction more if the alloy is thicker, but not much.
 

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Registered 2009 SLK55 AMG
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Discussion Starter #14
Thanks Durk, you are an excellent source of technical info. Appreciate your help as well as the others that spent their time in replying to this thread.

One last thing, would you mind sharing your opinion on calliper overheating and temperature dissipation with 17" vs 18". I consider it negligible but some have said that my calliper pads will last a lot less and I may face brake fading.
 

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Premium Member 2009 SLK55 AMG
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One last thing, would you mind sharing your opinion on calliper overheating and temperature dissipation with 17" vs 18". I consider it negligible but some have said that my calliper pads will last a lot less and I may face brake fading.
Yeah, that sounds pretty bogus to me :D.
 

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Registered 2009 SLK55 AMG
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53 Posts
Discussion Starter #16
Got the 17" front wheels, looks good on radial clearance (calliper - wheel circumference).

However, the new wheels have an offset of 47. The spokes touch the calliper front face and leave a pretty good gap. See pictures.

I believe I will need at least a 15mm spacer in the front as the original rims are ET37.

Any good/bad experiences when fitting spacers in AMGs? The vehicle has a heavy front and I don't want the lug bots to seize.

Recommendation on design with recess to fit the hub?

Thanks,
Fred
 

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Registered 2009 SLK55 AMG
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53 Posts
Discussion Starter #19
That is right Hal, it came from a C250, AMG. The wheels are 7.5" wide (front), ET47. Mine are also 7.5" wide, but ET37.

I believe 10mm spacer should be enough since the offset number referrers to millimeters, hence 47-37=10mm, correct?

Another question I have is the lug bolts. Obviously they will need to be longer by the thickness of the spacer. However, I was just looking at some tables H&R, the C250 rims were meant to be used with bolts M14 (14mm thick), while my SLK uses M12 bolts.

H&R supplies a kit for to fit the SLK with bolts. Would that be an issue? or the bolt heads are the same for both M14 and M12?

Unfortunately I just left Brazil in a business trip some 20k miles away. Wont be back until 15-Nov. I wish I could measure and compare the bores on the rims when I was there yesterday!

Thanks for sharing your technical background!
 

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Registered 2014 SLK250
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No, you will need bolts that have been adapted to use the later wheels on earlier cars. The bolts must have:

M12 shank
M14 Head
R14 ball (this in reality is important - there is a weaker seal using M12)
length of the spacer plus your original.

The length on yours is critical - if too long there is a risk of fouling the handbrake gear on the rears. If you cannot get ones with exactly 10mm extra length, then get the next longest and cut them back - or if only a few mm longer, bolt the wheel up to the rear hubs and rotate them. If they do not catch on anything, then you are ok.

I do not know about any kits that HR make, I would definitely ask fthem for the spec before buying. A good place for lug bolt specials and spacers is from a place in Germany that Sneaky Pete - a fellow forum member - gave to me who are extremely good:
spurverbreiterung - Index
 
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