Awd front tire wear???

I can't seem to keep tires on the front of my 2001 awd Astro. New idler arms, shocks and tires this time last year; 15,000 miles later bald front tires! Had alignment checked and garage said it was within specs, doesn't seem to pull or wander on the road. Inside and Outside edges of both tires are worn, but driver's side seems a little worse. Can anyone lead me in the right direction here? I've been looking at other Astro's in parking lots and have yet to see one with tires as bad as mine!

What kind of tires, what was the mileage rating of the tires, whats the air pressure in the tires?

Tires are Uniroyal Tiger Paw AS6000, rated for 50,000. Kept at 35 psi at all times.

I'm wondering if the torsion bars are getting weak and the front end is sagging?

I assume the garage checked the upper and lower ball joints that could cause your problem.

Reading tire wear is a lost art. I'll try to explain: Smooth tire wear on both the inside and outside edges indicates low tire pressure. If the wear pattern is jagged and symetrical, it can only show up on either the inside or the outside edge, not both. Toe in needs to be adjusted. If the wear pattern is not symetrical, look for worn suspension parts, ball joints, shocks, control arm bushings, etc. If the wear pattern is smooth and symetrical on only one edge, camber needs adjustment. Saggy torsion bars will affect all alignment angles, (Camber, Caster & Toe). Front ride height needs to be checked/adjusted BEFORE the alignment is performed. Hope this helps.