Narrowed control arms question

[cheford]

I have purchased a set of narrowed control arms from Porterbuilt to use on my 72 C10 and was wondering if anyone else were having problems with excessive tire wear, I only have 25,000 kilometers on this truck and have gone through 2 sets of tires on the front. It has been aligned to the factory specs of the 72 C10 and the shop that did it isn't getting any response of the situation from Porterbuilt. Is this a problem with the early Chevy trucks in general or the control arm geometry..?

John