I've got these tires and I'm wondering what PSI I should run them at to get a smooth ride, long tread life, and good gas mileage? If I can't have all I would like to have a smooth ride the most.

 

You might have to play around with the air alittle to see what you like best. 40psi is usally pretty good. Could do the water print test (wet your tire and roll to see if you have too much air, center of tread will be visable and fades to the sides. Too little air sides will be visable and fade towards center) Try to get it as flat as possible for best wear. Less air means softer ride

 

Those are a LR E tire. If the max psi is 65, us 45. If the max is 80, use 50.

 

I'd try 40 psi.