I, too, keep towing speeds to 60 max. Not because of tire issues, but because dragging a wall into the wind burns fuel at an exponentially increasing rate as speed goes up. 60 is where the rate of increase really starts up, but it is fast enough to run in top gear. When I was young and foolish, that didn't matter to me, but being old and retired, with no place to go and nothing to do when I get there has opened my eyes. Let 'end pass me, and waste as much gas money as they wish. I'll get there eventually and get to admire the scenery on the way.