I have 4 Bridgstons tires 4 years old with plenty of thread left. Now its looks like the outside edjes are worn more than they should. They call for 80 psi that is were i keep them. Should I go to 8...
I would not inflate above max sidewall pressure. At 40K miles, they have served you well. I do wonder if they are carrying a little more load than they are designed for, due to the wear you describe. Have you weighed your axles, to see if the tire max rating is a good fit? You may want to go up a load range with new tires, and then air to higher pressure.