Re: Suspension geometry problem
I'd be inclined to get a second opinion before doing anything major to your car. I might be doing the place concerned a big dis-service but on plenty of occasions in the past I've been to tyre places offering free tracking checks and found them to tell different stories! When I watch the lads using the equipment I'm not exactly filled with confidence! Don't be fooled by the "computer controlled 4 wheel alignment with lasers, sir" bit either. They're only as good as the bloke using them!
If you get two independent centres agreeing that it's 1.5 dgrees out (and both saying the same direction too!) then I agree it's worth looking further but as you say, it's not supposed to be adjustable and 1.5 degrees is rather a lot!
Incidentally, camber is one of the easier ones to check yourself. Get a straight edge the same length as the diameter of the rim and sit it vertically on the rim. Get another and rest it against the first and then get a spirit level on the back of that. Pack the tops (or bottoms) of the two straight edges apart until the spirit level is vertical and do the same sum that you've already done for the balljoint centres but using the length of the straight edge and the thickness of the packer. If you want something more permanent, I use an M6 x 1.0 bolt as the packer because one turn is exactly 1mm.
Finally, a lot of toe-out can also cause tyres to wear their inside edges out.