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2007 SLK350 Sport
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Discussion Starter #1
I have switched from the standard 16 X 7 - 37 mm (offset) front wheels and 16 X 8 - 30 mm (offset) rear wheels on my 2003 SLK 230 to 18 X 8 - 35 mm (offset) wheels on both front and back. Tire Rack and other resources "blessed" these wheels as suitable for my car. I have 225/40/18 Goodyear Eagle F1's installed. These are directional tires, so I now can rotate between the front and back on the same side of the car.

Now my "problem": on rutted roads the car frequently abruptly steers to one side or the other.

Any opinions on what is causing this..... other than the rut.... if anything? My guess in decreasing order of probability are:

1. The tires,
2. The offset of 35mm versus 37/30 mm standard
3. The use of a non-staggered configuration.

From what I have read in several threads in the R170 forum the non-staggered configuration is being used by several owners with no reported ill effects. My experience on good pavement has been excellent.

Thanks as always for your help.
 

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Golf R32 / Prev R170 SLK
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Black 2001 SLK 320 6spd
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76 Posts
What size tire did you have on the front before?
I'm guessing your new fronts are wider eg went from 205s to 225s so you will tram more.
Here's a good article about "tramlining" Tire Tech Information - Tramlining: Coping with the Ruts in the Road

I currently run your setup and where I live there is one really bad stretch of hiway ... I try to drive that stretch in the left (fast) lane. Less truck traffic ==> less ruts. I'll pull into the right (slow) lane if someone faster comes up behind me.

Cheers,
Mike
 

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2007 SLK350 Sport
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186 Posts
Discussion Starter #4
Rutted Roads

Mike, you are right, I went from a 205/225 setup to 225's all around. I wonder if owners that have gone to 18 inch wheels with 8.5's in front and 9.5's in the rear have the same problem. From Bazzel's comments the problem is common even with staggered wheels.
 

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Black 2001 SLK 320 6spd
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Staggered or equal all around shouldn't make a difference for tramlining, or if it does, the even wider rear tires would only make it worse. That section of the hiway I mentioned? It was way worse in my Boxster and I ran a staggered setup there.

As per TR's website...
"tramlining" is ... when directional control is disrupted by the vehicle's tendency to follow the longitudinal ruts and/or grooves in the road.

Noticeable increases in tramlining are frequently uncovered ... when any driver upgrades the performance of their tires using either the same size or going to a "Plus Size" tire and wheel package. The reason that it becomes more pronounced then is because ... the Original Equipment tires don't generate as much grip or responsiveness as the higher performance tires. Since the vehicle's suspension works as a complete package, a higher performance tire will also uncover any previously unnoticed looseness in the rest of the suspension.

So ... wider tires => more tramlining.
"Stickier" tires (ie more grip) => more tramlining.
Less sidewall => more tramlining.
Loose suspension => more tramlining (like Bazzle said)
Loose steering => more tramlining.

You upgraded to get better handling as in more control ie better "stick" ... downside is you are "sticking" to the road better now. Performance handling vs comfy ride ... its always a trade-off!

Cheers,
Mike
 
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I had Pilot Sports on the factory 17inch 32 rims and I really hated them on the freeway. You always had to be attentive to the road. I reluctantly changed out recently to Michelin PS2's based on a friends/mechanics advise.

WOW!!! Love um. The push and pull is just about gone. You can actually relax a little and what fun.

I don't know about 18's on a SLK, but 17's...18's...in my case tires! Different car.
 

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2007 SLK350 Sport
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Discussion Starter #7
poor handling

Great comments all around. Mike, your analysis really helps shed light on the problem and what contributes to it. I still have my OEM wheels with Michelin all season tires which I use in the winter. I'll report back on my experience. Also I was running my current F1's at 35 pounds. Now I have them at OEM specs. Based on the Tire Rack writeup this should help.

Denny
 

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2002 SLK 32 AMG, bone stock. 1987 190E 2.3-16 valve (destroyed). 2005 E320 new toy.
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Add to Mike's comments stiffer side walls, they will add to the tramlining as well. Going from one brand of tire even in the same size and performance category will change the tramlining characteristics of the car.
 

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Two 1998 SLK230s, 2003 SLK230 SE, 2002 ML320
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I have had 17s and 18s, both tramlined. I currently have 16s with factory Michelins on - no tramlining at all.
 

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2002 SLK 32 AMG, bone stock. 1987 190E 2.3-16 valve (destroyed). 2005 E320 new toy.
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I've been known to seek out ruts!!! :D

Seriously, most hiways have "ruts" due to truck traffic.
The Pennsylvania Turnpike is or at least was one of those rutted roads. Here in Maryland more potholes than ruts, but the intersections are in some placed seriously rutted. Coming to a stop can be a thrill……….. :D :thumbsup:
 

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2001 SLK 320(217K Miles), 2002 E320 Special Edition(183K Miles)
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It actually runs quite well on gravel roads and even off-road as well. The wide tires also makes it runs well in soft sand. :D
 
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