My 2004 Silverado 2500 Duramax calls for 60psi front and 80psi rear. That's what I run when towing. I don't think it is really wrong to run 80psi up front. It does not exceed the pressure rating of the tire. The steering may be a little faster with the higher pressure. You may feel more road roughness through the steering. Wear will be more to the tire center, since the front is not as heavily loaded as the rear.