Rear end wiggle
 

Hi all.
Are the OE Michelin Sport Pilot PS2 tires known to have a noticeable wiggle over rain grooves at highway speed?
My car is a 2000 Carrera 2D Coupe. I've driven it a total of about 6500 miles.
Its always had a slight rear end wiggle, most noticeable over concrete highway with rain grooves, but occasionally on road surfaces where the the surface is uneven and the camber changes frequently. The front feels fine, no feedback in the steering wheel, just a little twich from the rear.
It felt to me like the toe was off. I removed the drivetrain when I bought the car to fix an intermix issue so I figured I probably just altered the alignment in the process.
I had two new rear tires mounted and had the dealer do an inspection/alignment and balance all 4 and it still does it.
Anyone else noticed this?

I'm also driving a 2000 on normal Super Sports and I don't have any wiggle - that I've noticed. Maybe some dodgy engine mounts that you notice on rougher road?

Nothing but PS2s for 16 years and 80k. No wiggle even in snow/ice (contrary to usage guidelines).

Check the date code on the tires. They may be old and have started to harden which greatly reduces their traction quality.

+996 on being old, they shouldn't exceed 6 years from manufacture date

I did 6 years without realizing it. I don't recommend over 4!

I think 5 would be a happy medium!! haha

I was on 10 years for a little bit when I swapped over my wheels from 997 back to standard 996, would not recommend that. I basically couldn't drive in the rain...

It's possible for certain road surfaces to grab the tire and try to move it in a direction. I had tires replaced on my wife's 2002 BMW 325CI and thought something was wrong. Went back to the tire shop, had them check everything. Even after rebalancing and then having a 2nd tire shop check it out, we figured out it was the particular section of highway and those particular tires.

OP had two new rears instaled and the issue persists...

My 2000 C2 had a bit of a rear twitch (but I was on Continentals) that was most noticable under hard accelleration, which made me think I should have swapped the motor mounts. Sold the car and ended up with a C4 that does not twitch at all, but also seems to have motor mounts in better condition...

Good luck figuring it out. If this is your first 996, maybe go on a test drive with another 996 in your area to compare.

Ah missed that. Posting when tired is hard :( ;)

Still though, some shops have been known to use old stock so the dates are still worth a look anyway. Doubt they'd be more than 2 years old though...

I haven't heard of motor mounts doing something like this, but checking the suspension components might also be worthwhile. Particularly the control arm bushings?

The rain grooves are parallel with the direction of travel and grooves on your tires?

She's just wagging her tail cause she's happy.

Sounds like you're dealing with bump steer and believe it's coming from the back of the car. My C2 has bump steer, like most 996s. Some guys have added bump steer kits from aftermarket suppliers to counter this natural tendency of the 996.

If you post your alignment spec there are plenty of folks more educated than me that will verify if your alignment is correct.