On my '13 3500 I see the tires are rated 80psi max. The door says 60front and 80 rear. Just standard rims with tires. That seems high, unless towing. Considering the thing already rides like a tank at 45 PSI (new tires placed on by the dealership that is largely a truck dealer should know best, right? Maybe not). I don't want to shorten the tire life too much, but I don't want to be bouncing around every corner either. What do you run/suggest?