rusty spuds

I've had good service from the cross terrains. This past summer I towed a 2200 lb. enclosed trailer from N.J. to Alaska and back over hundreds of miles of gravel roads without a problem. I had several flats on the trailer which started the trip with new tires, and saw many cars and trucks with flats from the sharp stones. When I returned from AK there was a little over 39,000 miles total on the michelins and the tread measured 5/32" on the rears and 6/32" on the fronts so they had some miles left in them. I replaced them with the same since winter is coming and I wanted more tread than that for driving in the snow. I hope the second set holds up as well. 06 explorer 4.0