the ST tire from Hercules "Power STR" has a LRF of 3960lbs@95psi and a speed rating of 75mph....Most don't realize the speed rating of ST tires is 65mph...The GY Marathons I had on my 5th wheel just didnt hold up well on my Montana and after needing my 3rd tire all with in one year I to wanted to upgrade to a stronger tire and not go broke at the same time..I like to travel about 350 to 400 miles a day at 65 to 68 mph and so I needed a higher speed rated tire with a load rating of at least 3800lbs...The Hercules looked like the tires I wanted, so I bought 4 of them 3 months ago and traveled 1200 miles on them...holding up well and cool to the touch after driving 3 hours...Next year on my Trip to the Grand Tetons approx 4500 miles of driving will be my big test..Good Luck on your Tire Hunt....