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Discussion Starter #1
I've been tossing around my issue with the ride of my SLK320 in various threads and forums for a while now and between; old/bad tires, questionable shocks and possibly warn bushing, have found myself bouncing back and forth on how to tackle the problem.

Since buying my car a year and a half ago both myself and even my mechanic have commented on the ride quality of my SLK not being what we would expect from a Merc. I initially blamed the KYB Gas-Adjust shocks, which I am not much of a fan of, and even questioned at one point the springs on this car with only 94k miles.

Recently I have narrowed my focus to the tires themselves, and despite having 7/32 - 8/32 tread left on them am starting to think that between their age (2006) and quality (Uniroyal TigerPaw) they are as much the problem as everything else.

My question is; In trying to sort things out how would you guys proceed?

I had planned on starting with the rear end, and replace all my rear suspension parts with new bushings and a new control arm kit, which is costly if I go with a high quality OEM or MB parts, but their are lessor brands than even Meyle that can be had cheaply. I hesitate here, wondering if cheap bushings and control arms even if new are better than old MB parts with 90k miles. (MB parts are $500, Lemforder $380, Meyle $250 and Kayle- something is under $100).

Secondly I had planned on doing new shocks and had even contemplated doing new springs; although I hadn't decided on OEM or aftermarket parts (Sachs, versus Bilstein and HR and whether or not I wanted to get the original factory ride, or a firmer sporting aftermarket one new springs and high valved shocks would bring.

Lastly is the tires, part of me thinks I could just get a new set of quality tires and see if it helps, then work backwards, but since I had planned on upgrading to 18-inch wheels from my stock 17's, I almost want to work on the suspension first to see if I can feel a difference on the existing tires, before I go to a shorter side-walled tire. Is that foolish?

I'm sort of at a loss and figured I would toss my ideas around to the forum and see what you folks think.

Basically, my ride is harsh and bouncy, but I never bottom the suspension out or hear the requisite noise which would indicate bushing or spring issues. The traction in the wet is horrible and under braking I have no grip as well, leading me to thing the single biggest upgrade or change would be tires. However, I worry about tossing $800 or more worth of tires at a problem that might require additional parts and in turn wear out a perfectly good set of tires unnecessarily (if other components are bad, I don't want to trash a brand new set of tires while I trouble shoot). But at the same time, I worry about tossing cheap inferior parts at the suspension only to have them fail, or not work as well as even the current warn OE, although I would think initially at least any new would be better than ones with 90k miles.

As for the shocks and springs, I still don't know if I should waste my money/time here or not. The springs are the originals, the KYB's are obviously previous owner installed and would hope they were done more recently than longer ago, so would guess they have less than 40k miles on them. I had hoped to keep everything, under $1100 including tires so that makes it difficult to do everything, so I wonder. What say you guys?
 

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2007 SLK350 fastdawg
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I'm not driving an R170 anymore, but I can tell you that you might be thinking in the wrong order. It might be better to fit and sort out your tires and wheels first, and then go with the suspension parts. The reason I'm saying this is that you might need to adjust your height depending on the wheel/tire combination. If you do it the other way, you might have to redo your suspension to get it to look and fit correctly. Not to mention another re-alignment. Just a thought. Note: I'm going through that right now! :)

http://www.slkworld.com/general-modifications-r171/160049-new-tires-wheels-coming.html
 

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Dawg is right. Those are not the correct tires and are definitely too old. Get a set of something good like the Continental Extreme Contact or Michelin Pilot Sport and see how the car feels. While bushings may be going south, tires are more likely. My '00 C230 wore out it's front control arm bushings by 65k, but I autocrossed the snot out of it for several years so I wasn't surprised. Might also be shocks; I've always trusted Bilstein for my M-Bs when replacement was called for.
 

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Discussion Starter #4
I guess whats hard for me is getting my arms around how much difference a set of bad tires can make. I would have never put uniroyals or any similar brand on my car myself and appreciate that they are probably rubbish, but coming from years and years of tire purchases for other cars I can't say I have ever had handling issues or ride dis-comfort issue like I am seeing now. I don't doubt they are a big part of the problem, and I would give my left (insert body part here) to be able to sort out everything with a single purchase but am hesitant.

I guess it could be that simple though....
 

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I guess whats hard for me is getting my arms around how much difference a set of bad tires can make. I would have never put uniroyals or any similar brand on my car myself and appreciate that they are probably rubbish, but coming from years and years of tire purchases for other cars I can't say I have ever had handling issues or ride dis-comfort issue like I am seeing now. I don't doubt they are a big part of the problem, and I would give my left (insert body part here) to be able to sort out everything with a single purchase but am hesitant.

I guess it could be that simple though....
uniroyal are owned and manufactured by continental and are a premium brand :confused:
 

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2007 SLK350 fastdawg
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My ride on the 17 ' s seemed hard and loud, changed to 19 ' s with lower profile, the ride, noise, and handling is much better! The ride and noise part really surprised me. Worn tires on a car like this can really make a difference, shocked me!
 

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I would always say tyres first and go from there.
I was amazed at the difference a new premium set of tyres made to my first performance car.
In fact to the point the very first thing I do is check tyres on any vehicle I buy.
They must be 80% or more , good quality and balanced...
 

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Here's another vote for the Continental Extremes. They changed the entire ride of my car and they are fantastic in the wet. And they were only $135 each at my local family owned tire shop.

I cannot recommend them highly enough. Try them, you will like them. And they're very quiet.
 

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+ 1 for tyres first (AND take a look at the pressures too ... too high can make a pretty big difference to the handling..)

Once sorted, then look at the suspension stuff ...

Just my 2p's worth!

Cheers
Sean
 

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Discussion Starter #10
I am starting to think I have some flat spots on the tires or they are out of round. I want to over inflate them temporally and see if I can notice a difference, that should give me an idea as to whether its a tire issue or more.

As for tires.. for those who have recommended the Conti's are they the DW, or DWS? I am in Florida so have no real need for the 'S'-snow portion of the equation and have read a number of reviews on both that initially they are great, but do not last as long as others and tend to get noisier towards the end of their life (but what tire doesn't).

They are much more expensive, but I am considering the Michelin Pilot AS3's. Based on the reviews they last longer than most in their class and tend to offer a more comfortable/quiet ride, which is what I am going for since this is not my track car.
 

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As for tires.. for those who have recommended the Conti's are they the DW, or DWS? I am in Florida so have no real need for the 'S'-snow portion of the equation and have read a number of reviews on both that initially they are great, but do not last as long as others and tend to get noisier towards the end of their life (but what tire doesn't).

They are much more expensive, but I am considering the Michelin Pilot AS3's. Based on the reviews they last longer than most in their class and tend to offer a more comfortable/quiet ride, which is what I am going for since this is not my track car.
My Contis say "Extreme Contact DW Tuned" on the side; you certainly don't need a snow-rated version in Florida. I've had Michelin Pilot Sport and Pilot Exalto successively on my '00 C230 and have been very happy with their performance and longevity. Can't say anything about longevity of the Contis, as I've only owned the car about six months. It came to me with the OEM Contis on the rear with good tread, and new Uniroyals up front which I tossed for new Contis immediately. I abhor mixing tire brands on a car.
 

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+ 1 for tyres first (AND take a look at the pressures too ... too high can make a pretty big difference to the handling..)

Once sorted, then look at the suspension stuff ...

Just my 2p's worth!

Cheers
Sean
Sean, what would you consider too high? Mine have usually been set at the factory pressure, but this past weekend I used the factory "high speed" pressures since I knew I would be autocrossing and running portions of PIR at slightly above highway velocities. The tail seemed a little bit light, but with the caveat that I don't have a lot of seat time yet in this car in an autocross setting.
 

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Discussion Starter #13
I've been searching online and reading various reviews online for tires. I am limited by my rear 18x9.5 wheels in the rear, not many make a 255/35/18, or even a 245/35/18. Conti does though, as do Michelin and Pirelli and a couple others. Good and bad of it, most of the cheapo brands don't make tires in this category or size so that will keep them off the table.

The next big question and I am starting to agree that I need to do tires first, but the next question will be shocks. I am estimating there is less than 40k miles on the KYB Gas-adjust that the previous owner installed, but do not have much confidence in them from previous experience. I am contemplating going back to OEM Sachs or Bilstein B3, but again will depend on if I need springs due to the increased tire size
 

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Good and bad of it, most of the cheapo brands don't make tires in this category or size so that will keep them off the table.
Honestly, you don't want cheapo tires on any Mercedes-Benz. They are all engineered to perform best with a high-quality set of tires, and tire quality definitely makes a difference in comfort and handling. I would put Conti and Michelin at the top of my list and stop there.
 
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