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'14 CLS63 AMG S, '10 GLK350, '03 SL5000
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Discussion Starter #1
I’ve wanted to upgrade my 55 with wider wheels and tires while preserving the original look of the AMG 230 16-spoke wheels. I also wanted to upgrade the Pirelli P-zero Neros to Bridgestone S-03s which are sticker and my tire of choice. (It’s surprising that Mercedes would allow this AMG rocket to be shod with wheels and tires that are smaller than the less-powerful Crossfire roadster which runs 255/35x19s in the rear with 10 or 11 inch rims.)

CONCLUSIONS:

On the rear-- the 18x9.5 SL55 AMG 230 wheels from The Tire Rack (TR) with 255/35x18 S-03s fit just fine and add almost and inch of rubber on the road. (see photo below) However different (shorter) lug bolts are required.

On the front -- Recommendation: stick with the stock 7.5 wheels, but get stickier tires. However, the original wheels are very expensive. If the clearance in the wheel well is increased by trimming the front spoiler and rolling the fender lip (see info below) the 18x8.5 SL55 AGM 230 wheels from the Tire Rack with 225/40x18 S-03s fit just fine. This combination may fit without this modification, but I was not able to check this. This wheel with 235/40x18 tires does NOT work even with trimming the bodywork -- tires rub over large bumps with steering wheel straight. Shorter lug bolts are required for the SL55 wheels.

Here are 2 photos of the setup with the Tire Rack’s wheels front (18x 8.5, 225/40) and rear (18x9.5 255/35)



ANALYSIS:

Stock sizes on the SLK55 are:

Front: 18x7.5, Offset 37mm. MB wheel price: $ 875 each! Tires: 225/40x18
Rear: 18x8.5, Offset 30mm. MB wheel price: $ 945 each! Tires: 245/35x18

Tire Rack (TR) has not yet had an SLK55 to test for tire fitment but they do have the AMG 230 wheel in 8.5 and 9.5 x18 sizes for an SL55. And, correctly so before a real check, they have said that these will not fit. But I was anxious and I had moved the stock rear tires and wheels to the front and all seemed OK -- no rubbing with hard-over steering on a skid pad or with heavy braking. So after consultation and measurements with my local BigO tire shop, we ordered the following AMG 230 SL55 wheels and S-03s from The Tire Rack:

Front: 18x8.5, Offset 30mm. TR wheel price: $ 399 each Tires: 235/40x18 (TR currently shows these as unavailable.)
Rear: 18x9.5, Offset 33mm. TR wheel price: $ 389 each Tires: 255/35x18

The stock lug bolts do not fit the SL55 wheels because they are not threaded all the way to the seat so I also obtained the shorter (12mmx1.5 thread, 27mm thread length, 54mm overall length) bolts from a local shop. (see photo)



These TR wheels mounted front and rear just fine and everything seemed OK under heavy braking, hard-over tight turns.

In the rear, the 9.5 inch wheels and 255/35 S-03s are perfect and add almost an inch of rubber on the road. (See photo with 255/35x18 S-03s on the left, 245/35 P-zero Neros on the right.) I may even try a wider tire in the future.



However on the highway with wheels straight ahead when going over large undulations, the front tires contacted the front spoiler and the front fender lip in the fender well where the spoiler and fender meet. I trimmed the spoiler with a rasp and rolled the metal fender well lip under (click here http://home.earthlink.net/~hainesinutah/slkpics/wheels/wheelarch.jpg for a photo if interested) but the problem persisted very slightly on the right side only. We swapped the 235/40 tires for the stock 225/40 size and this solved the problem (with the spoiler and fender modifications.) I do not know if this 8.5 wheel with the stock tire and UNMODIFIED wheelwell will work -- I was not able to test this because I had already made the modifications. BTW -- feel and compare the fenderwell lip on the front and rear wheelwell. I don’t know why MB would not roll the front arch lip like they’ve done on the rear to provide more clearance. If you want to roll the front lip, you can do this with small strokes of a ballpeen hammer. Believe it or not, I used a smooth rock while I was on the road traveling! The rock now has blue paint on it and I’ve kept it as a souvenir.

But for now I am very pleased with this setup. I’ll have an opportunity to test it thoroughly in 2 weeks at Las Vegas Motor Speedway where I’ll be instructing at the BMW Club driving school. I’ll let you know how it goes.

Here's a link to another photo -- this one from my weekend at Pikes Peak International Raceway (Well, I'll have to admit that the tire patch is not mine -- it is one left over from the NASCAR boys or similar. Looks good, though, don't you think?


http://home.earthlink.net/~hainesinutah/slkpics/wheels/tirepatch.jpg
 

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2005 SLK55
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664 Posts
Thanks for the informative post...

Gordon, what is your opinion regarding the Kleemann LSD? I'm comptemplationg this in addition to wider rear tires on the OEM rims. And do you know how wide the tire can go with the 8.5 inch wide rims?
Fred
 

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SLK55 //AMG
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You, Sir, are an inspiration to a future AMG owner like myself.
Kudos!

Fred:
I was actually surprised that AMG chose not to include a LSD for the AMG models - the only AMG that has it in the USA is the SL65. A real pity in my opinion.
 

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2005 SLK55
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664 Posts
Another question...

Are these rims identical to the stock SLK55 SLK's? I'm thinking 9.5 rears only would be the way to go.
 

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'14 CLS63 AMG S, '10 GLK350, '03 SL5000
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289 Posts
Discussion Starter #5
RE: Original Wheel Info Follow-up

fredfromny - 5/2/2005 8:13 AM

Gordon, what is your opinion regarding the Kleemann LSD? And do you know how wide the tire can go with the 8.5 inch wide rims?
Fred
Hi, Fred.

WRT the LSD -- I really do not know how much performance gain it would provide -- perhaps it would be noticeable on the track, but for even spirited street use, I'd be surprised if it would be of much help. I imagine it is pretty $$$ and from a benefit/cost perspective it may not be practical. Also, there may be some interaction with the EDC function that would require some software changes to yield the full potential benefits. Also, I believe that adding LSD tends to increase understeer, so some suspension mods might be necessary (like a stiffer rear sway bar.)

WRT larger tires on the stock rims, I believe that 255/35x18 is the max for the 8.5 inch rims. Bridgestone has a spec page (for the S-03 but it should apply to any brand of tire for rim size) that is very helpful in this regard which you can find at

http://www.bridgestonetire.com/tireselector/dpp/sizespecs.asp?passproductid=227

WRT the Tire Rack’s SL55 wheels. Yes, in appearance they are a perfect match for our 16-spoke wheels -- they have the “AMG� logo imbedded in the rim. When I received mine, they did not include the center MB Star insertes, but I believe they have been shipped. You should confirm they are included with your order.

With this wheel, you will need different lug bolts which you should be sure you can find before getting the wheels. SL55 lug bolts will not work because although they are the correct length, they are 15mm diameter rather than the 12mm diameter bolts that our SLKs use. I got the bolts through my local Direct Tire, but I believe you can get them directly from Excaliper at excaliper.com. You’ll need 20 (plus a spare or two) of their part number C954. I’ve also ordered some wheel locks, but don’t have a part number yet, but the C954 part number should be enough for you to find the right locks.

Yes, I agree that the best option seems to be to use the stock rim on the front and get the Tire Rack's SL55 9.5x18 rims for the rear and go with a 255/35x18. Knowing what I know now, that's what I would do. I think a larger rear tire would also be possible with the 9.5 inch rim -- perhaps a 265 or 275 30-series but I'm not sure. There seems to be 1/2 to 3/4 inch clearance on the inside of the setup I have now. With an even wider tire, clarance problems may first appear at the outer wheel well arch over large bumps as I experienced with the front.

Hope this helps.
 

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2005 SLK55
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RE: Original Wheel Info Follow-up

Gordon-Just got back from my dealer to take a look at the SL rims. The SL's have 20 spokes compared to our 16 spokes. According to the tire rack page their SL rims are 20 spokers as well. So I think you did the right thing by nailing the last two front rims as there are none left according to tirerack. Oh well maybe its the Carlsonn 19's in my future.
Thanks for your informative posts.
P.s. the Kleemann LSD is around 2800 installed and is fully interactive with the ESP. I'm throwing a Pelloquin LSD in my FWD Audi TT this week so I'll see if I'm in love with the concept before spending another chunk of change!
Cheers
 

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'14 CLS63 AMG S, '10 GLK350, '03 SL5000
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289 Posts
Discussion Starter #7
I just counted -- 22 spokes!

Hi, Fred.

Well, I'll be....

I never did actually put the original wheels and the SL55 wheels side-by side. But I just counted -- the SL55 wheels actually have 22 spokes!

Really! I counted both front and rear twice. And I counted the original wheels also -- yes, 16 spokes.

Otherwise, they look similar, but you are correct. The number of spokes is indeed different.
 

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2005 SLK55
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664 Posts
RE: I just counted -- 22 spokes!

Can't wait to see some pics of those new rims on your car.
Certainly a unique look!
Thanks again.
 

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slk55
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Have a black slk55. I am looking for 18" aftermarket wheels and stock rubber. cosmentic change mainly. probably 8's in front and 9's in rear. renntech has some 18's in that size that they say "should" fit. they are made by oz and are supposed to be about 30lbs or so. also got a quote from wheelexperts.com for some hre's @$3,900. anyone have a weight on the stock rims? attached are the renntech offerings.

finally anyone found the black paint to be extremely scratch prone , especially on the plastic?
 

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