i once got a new set of tires that the moment i had them mounted and installed caused the car to pull to one side. i asked the tire shop to re-check everything since nothing had been changed aside from the tires and the car never pulled to the side before. i got it back and the problem seemed to have disappeared. during a routine check i discovered that they had pumped up the tires on one side to counteract the pulling! i lived with it for a while until i finally traded the car in not too long afterward. it was definitely the tires and had i insisted i might have gotten them replaced as defects...
1993 300e-2.8 - gone now <sigh>
"Do not adjust your mind, it's reality that's malfunctioning"