[james schaechter]

I have a 2002 GMC Duramax 6 speed stick 2500hd 4 x4 crew cab. It has 3.73's. I usually tow at 2,000 rpm (70 mph) It is stock except a k and n filter and synthetic oil. I tow a 24 ft pace. No topper. I get 22-24 when not towing can count on 16-18 towing. Better if I slow to 60. The Vrib Bridgestones are 2 mpg better on the highway. I have 176,000 miles on the truck and have gone back and forth on this. They suck in the winter so I now have a set of more aggressive tires for winter and road tires for the summer. BTW, I pump the tires up rock hard when on a road trip towing in good weather. In the winter, the cetane booster seems to be worth it in terms of mpg and power. JIm.