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Discussion Starter #1
I've been critical of the minimal rubber on the SLK55 and have upgraded mine a bit from the stock 245/35x18 to 255x35x18 in the rear (with wider rims) and stickier S-03s.

But seems to me that the Car & Driver comparison with 3 other sports cars demonstrates that AMG sold us short with the stock setup. The SLK55 excels in all categories except on the skid pad where it finished last. And there is some mention of wheel spin on launch.

And interestingly, I pulled out the prerelease road test in the Jan/Feb 2005 "The Star" (publication of the MB Club of America) and it lists the SLK55's rear tires as 275/35x18! Now that would be perfect. Any loss of acceleration due to the larger tires I'd expect to be offset by improved traction and the larger diameter tire would improve fuel mileage.

What happened AMG? Is there room for 275/35s in the rear on stock rims? Can someone try this please?

BTW, the Star article also shows the 55's front rotors with drilled holes but no slots. I've noted previously that on the driver side the slots are oriented incorrectly for maximum effectiveness -- not a big deal, but it's interesting that the 1st photos do not include slots.
 

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After reviewing the performance numbers noted in the Car and Driver review it appears that the tires work just fine. C'mon, 4.3, 12.7 and 0.91g are fantastic.
 

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slk55er - 5/7/2005 2:44 PM
...But seems to me that the Car & Driver comparison with 3 other sports cars demonstrates that AMG sold us short with the stock setup. The SLK55 excels in all categories except on the skid pad where it finished last...
Out of the 3 cars the SLK is the only one with a true front engine. Inertia from a heavy engine with mass beyond the front axial line is almost impossible to over come. The SLK should have been designed with the engine farther back. IMHO this keeps the SLK from being a 100% true sports car. When I popped the hood on my first SLK this was a major disappointment for me.

Unfortunately tires, LSD, or any suspension modifications will never erase this fact.
 

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Discussion Starter #4
GernBlansten - 5/7/2005 2:19 PM
C'mon, 4.3, 12.7 and 0.91g are fantastic.
Well, the 4.3 and 12.7 are primarily due to the engine and transmission and if anything, suffer due to the tires.

The 0.91g is last in the test and well below what an out-of-the-box M3 will pull. Since the relationship between lateral acceleration and velocity in a turn is a "square" relationship, a change from 0.91 to 0.96 (5.5 % increase) for example yields a 11 % increase in speed through a turn and a time reduction of 11% through each turn. M3s claim 1g -- yielding a 20% increase in speed over a 0.91 level. It doesn't take many turns for this to make a significant difference.

From my experiences on the track, the 55 really suffers in the turns due to being under tired, not just in a turn, but in applying power coming out. I've run with a front-heavy V10 Vipers and Corvettes and Cameros, and well-balanced Boxsters and M3s -- the SLK55 more than holds in the straights, but just does not have the grip it needs to take full advantage of it's wonderful drive train, brakes and chassis.

I'll bet that the next AMG SLK will have a lot wider tires (perhaps to match a 400+ hp 4-valve V8.) In the meantime, if you are really serious about extracting all the potential in your 55 (and perhaps the 350), I suggest that you'll need to find some better rubber.
 

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GernBlansten - 5/8/2005 9:19 PM

After reviewing the performance numbers noted in the Car and Driver review it appears that the tires work just fine. C'mon, 4.3, 12.7 and 0.91g are fantastic.
0.91g isn't outstanding, and you have to wonder what would the times be with more traction from wider tyres?
 

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ML500, SLK55 AMG
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slk55er - 5/7/2005 2:44 PM

But seems to me that the Car & Driver comparison with 3 other sports cars demonstrates that AMG sold us short with the stock setup. The SLK55 excels in all categories except on the skid pad where it finished last. And there is some mention of wheel spin on launch.
Which comparo used the SLK55? I have seen the 350 compared with the crossfire, boxter s, and corvette, but have not seen any comparo's with the 55. What issue? or is it on the web site?
 

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steve-p - 5/8/2005 5:53 AM

GernBlansten - 5/8/2005 9:19 PM

After reviewing the performance numbers noted in the Car and Driver review it appears that the tires work just fine. C'mon, 4.3, 12.7 and 0.91g are fantastic.
0.91g isn't outstanding, and you have to wonder what would the times be with more traction from wider tyres?
Read a long term review of the porsche 911 carrera 4S and they quote a 0.90g skid test. (also a 4.5 0-60 time after the engine was broken in). I didn't see in the C&D review whether the SLK55 was new or broken in, but it was posting better performance stats than an AWD 911.[:D]
 

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2004 SL600 Renntech ECU/TCU Upgrade...many other mods
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Why would we be surprised by being "under-tired"? MB makes no bones about not being track cars...except the Maclaren. I am proud that my car hangs with the $100K group on "shoddy" stock tires and at least $30K less, but then that's why I upgraded the tires and wheels to surpass the big buck boys[:D]. BTW...my 2004 Viper had poor rubber...I upgraded...my 2003 SL 500 had poor rubber...I upsized and upgraded...The only cars I see that consistantly don't need it are BMW M series and Porsche S or Turbos. IMHO
 

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SLK55er - thanks for your info. Did you purchase Bridgestone Pole Position S-03s? Are these the tires you are referring to? I had these on my Z3 and I loved the grip, but they rode very rough. So much so that I am not sure I would want to purchase them again. How do they ride on your SLK? Do you find that they grip better in the wet too? Thanks.
 

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Discussion Starter #11
Padd99 - 5/8/2005 3:21 PM

Did you purchase Bridgestone Pole Position S-03s? Are these the tires you are referring to? How do they ride on your SLK? Do you find that they grip better in the wet too?
Yes the S-03s. This is my 4th or 5th set, previously on several BMWs. Yes they ride firmer than the stock P-Zeros, but not excessively for me at least. The sidewalls are stiffer, but that is what yields a higher level of cornering and turn-in crispness The S-03 have a very high wet performance level. You can check the Tire Rack's site -- search for S-03 on their search page at.

http://www.tirerack.com/search/search.jsp

and you'll find some comparisons with other similar tires.

For complete info on my upgraded wheels and tires, please see the link at

http://www.benzworld.org/forums/forums/thread-view.asp?tid=1209178&posts=1
 

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I think a lot of people would agree with me on this forum that the S-03's are probably the best street tire they've ever run on. I swear by my S-03's (and my Valentine One)...I've had them on my Civic (215/45/17) and I could corner so fast and grip so well I was keeping up with Boxsters in the corners. For that much power that the SLK55 is pushing out, I'd recommend at least 19x9F/19x10R running 265/35/19F and 285/30/19R with S-03's. I'm just waiting for my stock Primacy's to wear out so I can get new rubber. Tell me how it goes, I'm curious to see what wider S-03's can do for a 55.
 

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The SO 3'S are very good, no question. I've had 'em on BMW's and have them on the SLK 32 AMG.
They DO definitely ride very,very--shall we say, "firm".
Frankly, since I don't street race, I'm looking forward to the Primacy or P Zeros to see if the ride's a little more "accomodating".
Am I wimping out?[:I]
 

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TLM - 5/10/2005 8:51 AM

The SO 3'S are very good, no question. I've had 'em on BMW's and have them on the SLK 32 AMG.
They DO definitely ride very,very--shall we say, "firm".
Frankly, since I don't street race, I'm looking forward to the Primacy or P Zeros to see if the ride's a little more "accomodating".
Am I wimping out?[:I]
The P-zero's are the quietest of the high performance tires IMO, which is important for top-down driving.
Cheers!
 

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Speaking of which, can anyone who has changed their stock Primacy's to S03's or better tires tell me how much of a difference it makes? I'm currently still on my stock Primacy's and I need to see if I should change them out for S03's or other ones before I take it out to the track next weekend.
 
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