My car (Gti with 17" GY F1 Asy) was developing saw-tooth inner tread block on the rear, so I stuck it on a rig, and the rear was miles out (amusing amounts of rear toe-out). Since correcting this and also re-setting the camber the tyres are starting to wear back to true, and rear tyre roar is reducing too.
Normally alignment on a decent rigger (hunter or equivalent) is about £25 per adjustment, so £75 on the gti with front toe, rear toe, and rear camber.