I was surprised to get that kind of mileage also but it has sure helped my cost per mile on running my truck.
My original tires were Goodyear Wranglers from the factory and I got 82,277 miles on them when I got the Michelin's this last year. I've got the stock 215's that I keep at 65 lbs all around and I rotate faithfully between 6000 and 8000 miles. Other than that I'm sure these straight flat South Texas and Louisiana roads are easier on tires than mountain roads, etc. I don't pull a trailer, but I frequently overload the truck and nothing's complained yet. (fingers crossed).
The truck is 8400 lbs empty (4200 front axle - 4200 back) and I have grossed up to 16860 lbs.
I got my new tires yesterday at 2:00 pm and I just now came back to the house with 900 miles on them, so they've been broke in already.
As for the alligator: I was hauling a 3000 lb offshore basket full of oifield rental tools one night going to Cameron, La. I was about 1/4 mile behind a car and just kind of following their taillights when all of a sudden I saw a 14 ft alligator across the road. His head was already off the road,his body streched across my lane and his tail was halfway across the other lane (the lane's are 10 ft from center line to shoulder). I ran over him at about 60 mph and it send the whole truck airborne. Evidently when I hit him, he was pretty PO'ed because he ended up biting my right rear outside tire in several places. To make a long story short, it didn't hurt the truck, it did kill the alligator, and I found a tooth in the tire when I had it replaced.
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1997 3500 club cab, 10' flatbed, 3:54, auto, 4 Firestone air bags, 236,000+ miles