Steering drift

[yelcab1]

My friend's 996 (2004 tip) has a strange thing that happens every time he drives it. On perfectly flat, smooth, high way speed road, one in a while, the car would just drift over 6-8 inches without any steering inputs.

What can be the problem?

[LanceGT4]

How many miles on the car?
When was the last alignment? any comments on tie-rods or rear bearing?

re-torque all the wheel bolts.
check the tire pressure.
I see you say flat, smooth highway.

Windy day? :-) sometimes a quartering wind will move me around some.
let use know what your friend finds.
Luck to you.
Lance

[yelcab1]

Problem found: 10 years old tires.