Between 30 to 40 MPH I feel what I can only describe as tire squirm. The tires have only 8,000 miles on them and are Sigmas, made by Cooper. The steering wheel doesnot wiggle as much as the body (I can feel it through the seat). I know that a rear wheel bearing has a little slop in it. The alignment seems good as the car tracks straight. Any ideas an what this may be will be appeciated.


thanks, thebern

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1982 240D 313,000 (4 speed)
1984 300CD 172,483
1985 German Shepherd Dog -Lacey- R.I.P.11/04/05

Hood Stars, Wrist Crowns and Obsession Dobs

Does it happen in a straight line or in turns?

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Never a dull moment at Berry Hill Farm.

Tire inflation? Check your pressures, front and back.

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Proud owner of ....
1971 280SE W108
1979 300SD W116
1983 300D W123
1975 Ironhead Sportster chopper
1987 GMC 3/4 ton 4X4 Diesel
1989 Honda Civic (Heavily modified)
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Section 609 MVAC Certified
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"He who fights with monsters might take care lest he thereby become a monster. And if you gaze for long into an abyss, the abyss gazes also into you." - Friedrich Nietzsche

If this only started happening when you put these tires on then it may just be a characteristic of the tire tread. Some designs seem to follow ridges in the road worse than others.

If the condition has developed a while after the new tires then I would suspect your alignment. It doesn't take too many potholes or bad roads to put the alignment out. Worn suspension parts will also cause mis-alignment, so these should be checked. Be sure to get a 4-Wheel alignment as the rear can be almost as problematic as the front.

New tires will exaggerate bad alignment since they will be square to the road while your suspension may not be. Worn tires wear into the alignment so the problem isn't as easily detected through the steering wheel.

Andy.

Rear subframce bushings?

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'85 300SD (formerly california emissions)
'08 Chevy Tahoe
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Every time I have had something like this, it has been an incipient tread separation: one side of the tread could be beginning to separate itself from the carcass of the tire. Eventually it may throw the tread, followed by a blowout.

Jack up the tire and feel along the tread for a bulge. The solution is to replace the tire: it can't be fixed, only replaced.

Assuming that this is the problem. It won't hurt to check.

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1990 300D 2.5 Turbo sedan 171K (Rudolf)
1985 300D Turbo TD Wagon 219K (Remuda)

"Time flies like and arrow, yet fruit flies like a banana"
---Marx (Groucho)

Every time I have had the back of the car tend to wobble, increasing with speed, it has been due to a tyre bulge, either de-laminating, or bulging due to air leak between ply and sidewall. Once I had this happen so I stopped. By the time I changed the tyre, I had a bulge the size of a football on the inside of the tyre. This was on a 4WD which was used for off-road work, but occurred on the highway.

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Tony from West Oz.
Fatmobile 3 84 300D 295kkm Silver grey/Blue int. 2 tank WVO - Recipient of TurboDesel engine.
Josephine '82 300D 390kkm White/Palamino int.
Elizabeth '81 280E, sporting a '79 300D engine.
Lucille '87 W124 300D non-turbo 6 cylinder OM603, Pearl Grey with light grey interior


Various parts cars including 280E, 230C & 300D in various states of disassembly.

Sigma Regent tires are junk, a 14 in size was recalled, not my 205-65-15 rear ones also feel bad.

If it's not pressure then it could just be the tread. Some tires I've autocrossed on had a bit of tread squirm at the limit. Uncomfortable, but if there's no bulges/separation, not dangerous.

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1984 300TD

I've had the same sensation before.... Always wondered what it was. Tire eh? Of course, Goodyear TripleTreds are kinda extreme tread-wise, so i can see how they might groove-follow to some degree.....

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-Matt

EPA Section 609 Certified MVAC Technician
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Oil Burner Kartel Member #10

Ahh the smell of Diesel Fuel, it's like coffee in the morning!

My Car:

1982 300SD Turbo Diesel (231,500 miles!) RIP

1984 300SD Turbo Diesel Custom (235,500 mi on driveline.) - On Road!!

www.icsrepair.com

Thats my guess.

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green 85 300SD 200K miles "Das Schlepper Frog" With a OM603 TBO360 turbo ( To be intercooled someday )( Kalifornistani emissons )
white 79 300SD 200K'ish miles "Farfegnugen" (RIP - cracked crank)
desert storm primer 63 T-bird "The Undead" (long term hibernation)

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The way I understand it, tread squirm is kind of mushy wiggle from the tire, not groove-following. Groove following could be the tire, or too much toe out.

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1984 300TD

Replaced ANOTHER tire now, makes it both front AND rr tires with bad ply separations. I can already feel the lr tire is next. Major quality problems with these tires make by Cooper tire! Tires came on my 300sd I bought a couple months ago, previous owner died, one of the few receipts I don't have is for the tires. Basically the tires work fine then a vibration starts and quickly gets worse over a couple days. Good faith replacement? I don't think I want them on any car I own!

I've explained this to Matt in the past regarding his Goodyears. But, it will apply to your Coopers as well:

Michelin makes round tires.........Cooper makes black ones.

I don't know the load rating on the cooper tires, but I had a heck of a time finding tires locally that were rated for the weight of my SD. It might have some bearing on the repeated sidewall blistering, if they're not rated for a vehicle this heavy.

That being said, I've had bad problems with some makers of tires, even on light cars. The Pirelli's that I had on an older Isuzu Impulse (VW Sirrocco look alike) blistered at least three times. That was the car that made me a firm believer in road hazard warranties!

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-Josh
Testing the cheap Mercedes axiom, one bolt at a time...