We tow our Airstream with a Chevy 3500 single rear wheel. My guess is the tongue weight of the trailer is about 1,200 lbs and we have another 1,500 pounds of cargo, people, and fuel. We have 25,000 miles on the truck with 16,000 miles towing. I'd say the rear tires are about 2/5 of the way to the wear bars. This should extrapolate to the tires being worn out at 50,000, which seems to me that we should get better wear. Do you think this wear rate is normal, or would you expect a longer life from the tires?