Expl99..if they are wearing badly then it might not be the psi...but then it might...but if they wear bad and you think your psi is ok, then there could be a suspension problem. It could be something out of alignment, just a tiny bit, causing it. In my case, I had a bad shock that was beginning to cause odd wear on the outside of the fronts. I fixed the shock, rotated, and no bad wear on the tires in front now.
Ru-M, Maybe Ford set a different psi for front/rear between XLT's and Sports...since XLT's have the longer wheelbase, and higher weight...
But I figured since 91 to 94 are largely the same truck, Ford would send the same sticker to everyone.