Your dealer can recalibrate your computer to recognize the 285's. That's the largest size tire that the dealership's computer can take it to. It should be about $45. Once that's done, you should notice the overhead consule reading a little more accurate.

I added 315's and it dropped through the roof (according to the overhead)! I had the recallibration done and it brought it back to near real-world results.

 

me too. I get nasty injector rattle til i add some lubricant in the form of STP diesel additive or Power Service.

 

I did 800 miles this last weekend with my XZT box, my mileage on paper was 23.5 averaged between 60 and 75 mph 95% highway and the 5% going slow thru towns, I cant waite for some good fuel, but winter will end in about 2 more months up here.

 

ARe you running stock tires??

Shane

 

USLD stinks....it is the devil!

 

The fuel thing is 1 because of the new low sulfur fuel and 2 the winter blend in the diesel. The tire spedo. issue I put 315/70/R17 Mickey Thompsons on my truck I took it in to the dealer and they recalibrated my truck for $20.00.

 

Don't know what year truck you have, but if it's new I'll bet ya a beer it's only calibrated up to a 285. Watch you're speed, you're really going faster than you think.