[msej449]

The first thing in these situations is to take it to have a full tracking check/adjustment at a specialist tyre outfit. By specialist I mean somewhere with a full Hunter setup and someone qualified to use it. Most every tyre outfit can do tracking, but only a minority have a Hunter (or equivalent) system - it's the latter you're after.

A full Hunter tracking check will either correct the issue, identify the cause, or at least eliminate that it's anything to do with tracking setup on the car. At my tyre independent, it's obvious that the tracking guy is one of the more mature guys in the shop: he clearly doesn't do grunt work fitting, but specialises in balancing and tracking and talking to customers about tyre choice etc.

At the same time, they can check the individual wheel balancing and things like the aforementioned balance weights coming off, bent rims, flat spots etc.