How does your R129 Sport w/ 18"ers ride? - PeachParts Mercedes-Benz Forum

lynns · #1 08-24-2006, 03:12 PM

I have a 2000 SL500 with the Sport package. This includes Yoko AVS dB S2 245/40ZR18 front and 275/35ZR18 rear, high-performance tires.

I have had the car aligned and all four tires trued and balanced on the car w/ no bent rims. Set at 33 and 36 psi w/ Nitrogen.

I get a rough ride plus vibration on most stretches of freeway. Only the smoothest of road conditions up to 60 MPH and after 80 MPH are comfortable w/ the convertible top.

I'm confused about the out of balance like vibration between 60-80 MPH ???

My prior ride was a 1989 560Sl with new 15" Michelins set at 28 psi. What a smooth soft ride.

iwrock · #2 08-24-2006, 03:17 PM

The bigger a sidewall on the tire you have, the more bumps that the tire can absorb. So, when you have 18 inch rims, and a very low profile tire, the tire cant absorb as many of the bumps as a regular tire.

I have 18s on the SL600. Its got a very nice ride, but you can feel the smaller bumps on the freeway. We had a set of 16 inch wheels on it for a month while one of the rims was getting the curb rash taken out. It had a VERY VERY smooth ride, as the tire was able to absorb a huge amount of the impact from freeway bumps.

jdonnee · #3 08-24-2006, 03:55 PM

I have 16 inch rims with new Cooper Sport profile tires and had them inflated to 34 PSI all around . The ride was very hard and bumpy. I ended up with the fronts at 28 and the rears at 30 and now the ride is very comfortable. I have not seen any increased tire wear. Dont know if this will help you.

Pete Geither · #4 08-24-2006, 04:30 PM

I have a staggered 17" setup I use for around town and short trips, but any long distances I put the original 8 hole 16"s on for the ride and if I would have a problem with a tire, I would have a much easier time finding a 16" over the staggered 17" setup. The 17's are much harder to balance perfectly also since they are not an OEM wheel, the 16's are perfectly balanced.

Mike Miller · #5 08-24-2006, 05:42 PM

I have Kumho, 245/40ZR18 front and 275/35ZR18 rear's. My ride is understandably "stiff", but not what I would call harsh. I have all new rear suspension parts and all new shocks. If I wanted a ride like cloud nine, I would buy a Cadilac.

toniyturbo · #6 08-24-2006, 08:58 PM

i have the new 230 wheels on my 1996 129 front 255/40/18 back 285/35/18. it rides very very smooth. i dident like it too smooth so i switched it back to 245/40/18 - 275/35/18 bridgestone so-3's all around. now it drives like how i like it to drive. one question do u have ads suspension on ur car?. that makes a difference too.

lynns · #7 08-24-2006, 10:18 PM

Thanks to all for your reply.

I do not have ADS. I understand that there are not many SL500's w/ that option. Usually found on a SL600.

I'm not looking for a Caddy ride. I only want this $90K car to ride vibration free with the hartop on or off. Up or down. Especially between 60-80 MPH on a smooth freeway. I can understand a rough ride on a rough road surface.

Trust me when I say I have felt the difference when a suspension is tuned. I had a 280Z that had new BF Goodrich tires that where tire trued and balanced on the car and road great afterwards. No vibration at any speed.

Lee Blaik · #8 08-25-2006, 12:54 AM

I switch from 16" to 17" using Mercedes fan style chromed rims (love them) and shed 245/45/17 Conti Sport Contact all around.
Took me three trials to balance them right as the lower the profile the more noticeable the imperfections and vibrations. Ended up using my local MBZ for the best balance.
You don't wanna sacrifice the ride or the look. One must seek a happy medium, I guess.
Cheers to all...Lee

lynns · #9 08-25-2006, 12:26 PM

I am taking the car into a tire dealer today for a Hunter Road Force evaluation. I will post you with the results.

lynns · #10 08-26-2006, 03:34 PM

I had my tires Hunter Road Forced @ $100. The computer said all of my tires balanced out with one rear 275/35/18 that needed to have the rubber shifted on the rim and rebalanced. They also pointed out that the weights from the prior on the car balance were self defeating. So I said go ahead and rebalance all of the tires with the Hunter.

I then took the car out on the same smooth stretch of freeway and ran it up to 90 and let her coast back down. I now have more vibration between 60-80 MPH than when the tires were balanced on the car.

This is a total of 3 different dynamic balancing techniques, 2 off the car, 1 on the car, as well as Tire Truing for a total of $380.00 at 4 different stores and 6 trips .

I was so frustrated that I took the car to Fletcher Jones (MB dealer) and a Service Advisor with 18 years took a test drive. He suggested that even though I have had all of the specialty alignment work done that I may still have tire problems. His suggestion was to replace all four tires with Michelins. I'm thinking the Pilot Sport PS2 at Costco for a OTD price of $1256.

Your thoughts please!

5280BENZ · #11 08-26-2006, 06:10 PM

This chart may help you decide.

http://www.tirerack.com/tires/surveyresults/surveydisplay.jsp?type=MP&width=245%2F&ratio=40&diameter=18&tireSearch=true&rearWidth=275%2F&rearRatio=35&rearDiameter=18

Lee Blaik · #12 08-26-2006, 06:41 PM

Lynn
Before you invest in new tires you may want to check your motor mount.
If all is well than Michelin or continental are the best of course.
Good luck.
Lee

lynns · #13 08-26-2006, 08:44 PM

Quote:

Originally Posted by Lee Blaik

Lynn
Before you invest in new tires you may want to check your motor mount.
If all is well than Michelin or continental are the best of course.
Good luck.
Lee

Lee,

Thanks for the suggestion. Thats the kind of thing that I am looking for from the forum but in this case my Indy evaluated the car and I asked him to check the motor mounts and sub frame mounts. His reply was that they looked good to him and that is what he would expect out of a 20K mile car.

Dr_Joe · #14 08-27-2006, 11:07 PM

I have the same problem !!!

My car has the staggerred 18's with the sport package. I bought it last year, and it had Dunlops on it, no vibrations at any speed.

I recently bought Sumitomo HTRZ II's and had a very harsh vibration between 60 and 85 mph.

Back to the tire dealer. He says the wheels are out of round, and I didn't feel it with the older tires because they had worn in to compensate for the high spots. He said it would probably go away.

1000 miles later it didn't go away, so I sent the wheels out to be trued, and refinished.

Remounted and balanced the tires, and still had the vibration. (it's from the rear) Close inspection of the tires showed that one rear tire had a little "hop" or irregularity in it's circumference.

Replaced both rear tires, re-mounted and balanced, still have the vibration !

It's driving me crazy !!! Below 60 it's smooth as silk. Over 85 it isn't bad, but I think thats because the frequency of the vibration is such that it's amplitude is lower, so less noticable.

I'm not sure what to try next, but it's very annoying. Driving below 60 on the highway is a drag, and driving over 85 constantly will probably cost me my license in a week.

HELP !!!

P.S. Motor mounts were changed 6 months ago, and all other suspension and driveline components have been checked.

lynns · #15 08-28-2006, 01:54 AM

[QUOTE=Dr_Joe;1259446]I have the same problem !!!

I'm not sure what to try next, but it's very annoying. Driving below 60 on the highway is a drag, and driving over 85 constantly will probably cost me my license in a week.

Doc,

It appears from what you say that you and I have the same problem. I would like to clarify one thing on my end. When I use the term Tire Trueing I mean the rim&tire are taken off of the car and placed on a machine that cuts the tire rubber evenly across the tread. They are then put back on the car and the rim&tire are strobe balanced on the car. I did it this way in hopes that I could get some additional wear out of these tires that looked like they had enough rubber to salvage. In lieu of a new $1000.00 purchase. Here is today's string at BenzWorld.org. This thing is driving me crazy.

http://www.benzworld.org/forums/r129-sl-class/1276395-how-does-your-sport-w-18-a-2.html

I sampled 2xSL600 and 3xSL500 today. All had different tire combinations. The SL600's had comfortable ADS suspensions. But I wouldn’t buy either of them. The SL500's drove well and I like the firm ride. The best car was the 2001 SL500 w/ 53K. That guy took care of his car and it road like I wish my car rode between 60-80 MPH. Note: It had brand new Pirelli's on the front. Wonder why???? Probably because they want to sell the car and don't want people complaining about a vibration between 60-80 MPH.

All of the cars drove reasonably between 60-80 MPH unlike my car. Note: They all had a minor vibe at 75 MPH. It is my guess that with all of the time and effort that I put into trying to salvage my Yokahama's was probably to no avail. I really don't think that the rim size is so much of an issue. I know from past experiences that all new rubber makes a car feel great. So I will keep my fingers crossed that new tires will solve my driving problem.