thanks, I tow a toy hualer(est. 8500lb total) from San diego to the desert on I-8. if you guys are not familiar it is mountains all the way. my truck gets up to 225. on the steepest grade, it only stay there for about 5 min. or so, then drops back down below 190. I average about 60 mph @ 2500 rpms, grades about 50-55 at 3500 rpm...... does this sound about right.