I agree that inflating max tire pressure is a sure way of getting your up MPG but I can not stand the jarring I get with high tire pressure. The wife complained that I have to do something to make it ride better. I now run 45 PSI on all four. Even with low tire pressure on my 37 I still get 18.5-19 MPG 10% city 90% highway...not bad for a 1 ton truck. I run my Smarty at SW #6 no timing. I hated the excessive pinging and rattle the even SW gave my truck. I did however do the tone ring mod for just a couple of degree advance. Anyone know how many degree the timing advance on odd # SW on Smarty?

 

As far as the ride goes,consider a Carli starter kit. It'll level the truck and give you a much improved ride.

 

80 PSI is cold pressure, already adjusted for use. I have 185,000 miles on mine going 1800 RPM, (no trouble) look at the power band of our CTD's. By the way I live in the desert were it can go from freezing to over 100 degrees, I've had no problem running over 1,000,000 miles at max PSI on my BFG's.