It is just common sense to check the tires and the grease in the wheel bearings but the biggest thing is to SLOW DOWN when it is this hot!! Speed generates a buttload of heat within the tires and heat equals failure.
It amazes me to see these morons pulling a boat down the interstate at 70-75 mph especially when the temps are 90 or above! Slow the damn thing down and leave 5 minutes early! 60 to 65 is plenty when pulling a trailer!
Anyone that has had a tire failure on a trailer at high speed with tell you how important it is to slow down.
I can promise you that a trailer tire blowout at 70-75 mph is not fun! I have seen the results of some idiot pulling a boat at 70 mph and having a blowout on the trailer. The trailer went sideways and pulled him into oncoming traffic. He lived and the two people in the car he hit died.......