25th May 2003, 13:54

We recently purchased a 1999 SLS that has this same vibration problem. We have had the tires balanced, but it was no help. Does any one have any ideas as to what "cherry picked" tires will solve this problem? Any help would be much appreciated. Thank you, Becky emerickhome@msn.com.

10th Jun 2003, 19:50

Well gang, you are not alone. I have a 2001 STS and been through the tire change routine… three sets (now have Michelin) and balancing on Hunter machines. I thought I had a good balance at an independent tire dealer. But the last time I did a tire rotation, felt that annoying vibration. Tire dealer said that the road force showed that the tires had deteriorated (improperly molded by bad suspension.) Went to web site, like this one, and know found out the Caddy has a control arm fix. I bring in the car this Thursday, June 12, and we will see what happens. I will keep you posted on the results.

19th Jun 2003, 09:08

Glad I found these comments! I've had my 2000 STS in twice for vibration problems. They worked on the brakes once and wouldn't say what they did the other time. I took it in again two days ago & told them not to call me until they resolved the problem. I talked to the service manager this morning & he said the steel belts had "slipped" in my tires & I need new ones. I would agree that the tires are nearing replacement from normal wear, however, I had the same problem a year ago when I first took the car in for the vibration. In fact it always vibrated somewhat at 70 MPH, but I just ignored it.

So... if I replace the tires & have the same problem, can the dealer fix it?

21st Jun 2003, 10:36

I have had the same problem with the vibration in my 1996 Cadillac Seville, as well as numerous other problems. The air compressor went out and had to be replaced at an enormous price as well as the alternator. I now must have the entire air conditioning system blown out because the lines are contaminated.

I am now have problems with the coolant, which seems to be disappearing for no reason. I have also had the water pump replaced. This car needs to be recalled to repair these problems, especially the coolant problem, which seems to be going back in the engine and dissolving or evaporating.

I have had this car four years, and it is the worst investment I have ever made. Never again.

1st Jan 2004, 21:43

Put some speed rated michelin's on your cadillac's, your future will be so much better.

22nd Apr 2004, 20:08

Hi Cadillac friends, I Just purchased a Certified 2001 Seville STS and have the same vibration problem. I have owned it 22 days and it has been in the Cadillac garage 13 of them. Cadillac has put on one new tire, both lower control arms and has force balanced the tires with no help. I am trying to take it back. What can we do? With the cost of a Cadillac they should be better.

12th May 2004, 18:09

Fellow caddy lovers, I just bought a 2001 STS with 30000 on it. This is my fifth caddy and my newest. I do notice a suspension problem on corners and over rough surfaces. I had a suspension code come up so I took it to caddy where they said they updated the computer and that was it. How could updating the computer fix the suspension. Also the moonroof won't stop rattling. They say that they can't do anything, but lube it.I'm very unhappy with the car as well as the service. The car is stunning and has its strong points, but for the price of a caddy I feel, I should expect a bit more.

27th Jul 2004, 22:02

I bought my 1999 SLS off the showroom floor on a Saturday in Kansas City from the Cadillac dealer and drove it home to St. Louis, shaking and vibrating all the way. Having driven Caddy's since 1981, I was sure a routine tire balance at my local Goodyear dealer would fix it. 5 years later, (and one new set of (Integrity) tires, plus numerous trips to the local St. Louis dealer) I still get the shakes every time I drive at highway speeds. Yesterday, I was having the car serviced and mentioned the vibration problem and the service rep spoke of a 2002 model that they couldn't fix, and GM bought the car back from the owner. But, that guy evidently got ugly right after the purchase. Too late for me. Anyway, someone mentioned speed-rated Michelin tires as solving this problem. Anyone to confirm this?? How about Bridgestone tires? They (are made in Japan) have a 30 day road test - return at no charge policy.

4th Sep 2004, 09:22

I just purchased a 2001 SLS with 19k miles. I have also noticed the tire vibration, usually under acceleration up hills, and always at highway speeds. The car has Michelin Symmetry tires (I assume they're original). Is this problem covered under warranty? It is still under GM bumper to bumper 4yr/50k, and also certified 6yr/100k.

Frostsdad@msn.com.

2nd Apr 2005, 20:53

I am a retired automotive engineer who spent several years working on tires. What the dealers are telling you is true, there is a lot of variability in tire quality out there. Tire companies have to meet higher specifications for Car companies than they do for the aftermarket, because the auto companies demand good tires. They have clout, that you don't. You can't hold that against them.

We consumers need to organize to set the same kind of standards for after market tires, but unfortunately the technology is not cheap enough for us to tell a good tire from a bad tire. Thus the tire manufacturers aren't going to spend the money to give you good aftermarket tires when no one can tell the difference, until after it's too late.

Tire balance is not the whole story, not even half the story. It is roughly one third of the story.

Tires have soft and hard spots in their structure, these spots result in a variable tire radius as the tire rotates under load. You cannot detect this characteristic with a balance machine, because the tire doesn't have the weight of the car on it (with the majority of balancing machines). But it will cause your car to vibrate at tire frequency (15-20 cycles per second). This "force variation" as we used to call it is a tire characteristic as important as balance.

The third factor is wheel and tire run-out. You can measure this, and it should be less than roughly 1.5 mm max. This is the tire center not coinciding with the wheel bearing center of rotation. You can balance such a tire, but you are wasting your time, since the radius of the tire will still change every revolution regardless of the balance, giving you a vibration.

I assume that the most expensive aftermarket Michelin or Goodyear tire would have good properties all the way around, but you know how expensive those tires can be, and we still would not have a guarantee of their quality, since these characteristics are not commonly measured or specified.

Some suspensions are more sensitive to tires than others, the suspension engineers endeavor to make sure they don't have anything in the suspension with a natural frequency in the 15-20 cycles per second range. They also often use the engine mount spring rate and weight of the engine to perform a dynamic absorber function in the critical tire frequency range.

Small front wheel drive cars with McPherson strut suspensions are rather insensitive to tire quality, I have found.

Another person above mentioned the Hunter GSP9700 balancer, which does apply a radial load to the tire while it is being balanced. Find a tire place that has one of these or equivalent for the best balance that will include the effect of tire force variation.