Steering wheel shake

[Sams]

Hi, I've got a 2000 Boxster S. When reaching 75 mph, the steering wheel starts to shake a bit. I've had the tires and rims checked, they are supposedly fine. The shaking is pretty light, it goes away if I hold the wheel firmly. I heard this might be normal with very stiff suspension, 17" wheels and not too perfect road surface, is this the case?

[Perfectlap]

I get that too. Usually before the tires are up to temperature. Tires also tend to harden after a certain amount of miles, only so many heat cycles. The harder the tire the more likely to get vibrations from irregularities on the tire surface like flat spots.
Do you only notice the shake on short trips or during longer ones as well?

[Sams]

Originally Posted by Perfectlap

Do you only notice the shake on short trips or during longer ones as well?

The shake is always clearly noticeable when I reach 75+ mph no matter how long I've been driving, switched the tires a while ago but it made no difference.

[Perfectlap]

when was the last alignment?
My previous car (Miata) had a notorious 65mph shake, that went away if you went above 65mph. After several alignments and different sets of wheels it still had the shake. I wonder if this is inherit in rear wheel drive cars.

Originally Posted by Sams

The shake is always clearly noticeable when I reach 75+ mph no matter how long I've been driving, switched the tires a while ago but it made no difference.

Hi Sams, are all of the tires the same brand/type?

[AtlantaBoxster]

I had the same problem starting at 81 mph. I went to Butler Tire in Atlanta and they did a high speed alignment. Paid $130 and the problem is gone. I was told by less experienced shops that it is feathering of the tires (they must have seen a lot of the 350Zs).

You should look into getting an alignment done by a professional shop, not your run of the mill Firestone or local garage.

My 0.02.

Good luck on getting it resolved.

[jiggysubman]

there was a thread started by myself titled "steering wheel shimmy" with the same exact problem. I tried various things, and eventually just took it the the local porsche dealer to have the tires balanced. Now they're perfect. The dealer claimed that most tire shops don't have the high speed super-duper balance machine that they have. They did my balance for free, but others have reported around $100 for it. That price is worth it, and once you get it done, they will do it as much as needed for the life of the tire.