A tyre that handles well on omega will drive straight without tram-lining for, say, two thirds of the tyres life. Approaching 1,5mm off the wear indicators it will start to pick up wheel tracks in the road, assuming there's no faults on the car.
A bad handling tyre on omega will start off handling like a worn good handling tyre as described above, and degrade to the point it becomes dangerous, and very difficult to keep in lane on poor surfaces.
So, what tyres, and how worn are they? Is the wear even across the tread? Pay special attention to the inner edge on all four tyres.
If the wear is uneven, your most likely looking at bushes and set up. But tbh. Unless the bushes have been replaced, most cars this age will need new bushes and set up by now.
There are guides in maintenance and FAQ re handling issues.
But generally speaking;
Check and rectify suspension and steering faults.
Set the car up for full geometric set up, which includes camber. See wheels in motion web site.
Then fit new tyres once happy.