I took my truck this weekend to 4 Wheel Parts to have them check out a wobble noise in the front tires.
Upon inspection, the senior techs there told me that my tires were cupped ( Procomp 33x12.50x17 - 15000 miles on them )
due to the fact that the torsion bars were cranked up beyond the recommended. (???) Their solution to the problem was to lower the front end back down to factory, align the truck, and sell me two new tires since the tires that were cupped will not be corrected by either of the two remedies.

How would they know what the recommended torsion bar adjustment is?? Does for put a spec out on that?

bottom line according to them:
Cranking torsion bars is bad for the tires and should not be done.
They of course wanted to sell me a 4 inch lift kit after that.

 

You know, I ran into almost the same thing. I cranked up my torsion bars also. I drove the truck for 2 weeks and didn't notice any indication of the front end needing an alignment. Since my truck was only 7 months old and warranty would cover an alignment, I decided to have it checked. When I picked up my truck, I asked the service manager how bad it was out of alignment. He said it was out of alignment slightly and showed me a printout. I then took my truck across the street to my tire dealer for my free tire rotation. They also do alignments so I was talking to the technician and told him that I had the dealer check my alignment because I had cranked up the torsion bars and heard that it would screw up the alignment. He said that it would indeed throw the alignment off and also said that sometimes he had to take some of the preload off torsion bars to get trucks to align within factory specs. Well this got me to thinking. I didn't tell my dealer that I had adjusted the torsion bars, I only told them that I thought that the truck was pulling to the right. I started looking at my truck and thought that the front was sitting slightly lower. I crawled under the truck and sure enough, they had backed off the preload. I measured and the truck is higher than it was when I bought it, but not as high as I had adjusted it. So I guess that torsion bar preload does have an effect on alignment and is apparantly something that is adjusted during alignment. I probably would have questioned this, but it was funny that an alignment tech at another shop mentioned it.

 

If you look at the A arms on the front suspension you'll notice the top and lower arms are not equal length. This would mean that the tire/wheel would change camber slightly in it's up and down movement and possibly be off-camber if you cranked the torsion bars. Of course toe-in could be adjusted but not camber if you're suspension is radically adjusted. So the tires would wear out faster on either inner or outer edge.

I would swap the cupped pro-comps to the rear axles, lower the torsion bars slightly, have the camber/toe-in checked and run with it.