Ok, finally got around to getting the shorter tires on my van this past week. Replacing the 29" 235/75's with 28" 235/70's and 275/60's (front and rear) With the 29" tires, the "sweet spot" in the engine's powerband started at around 70 mph (and went clear up to 80+) after the GT40 head swap (combined with the 1.7 Cobra roller rockers and new 3" exhaust with shorty headers) Before this combo was put together, the mileage when we bought it and drove it home from S. Texas was around 14 mpg. I never got the chance to check it after the head swap with the van completely empty, only loaded back and forth to Kalifornia from S. Louisiana where it averaged 10 mpg on the trip out and 12 on the trip back (trip back was towing a lighter trailer than the trip out) Today we made a 153 mile trip up to Alexandria La on I-49 with a stiff 20-30 mph southwest to northeast wind running at 70 mph both ways. It burned 10 gallons of gas, yeilding 15.3 mpg. So much for the shorter, wider tires burning more fuel than taller narrower tires. The key is in finding your engine's sweet spot and either driving at that speed or making adjustments to the drivetrain (shorter tires in my case) to allow you to cruise at a lower speed. Sure I spent a wad of cash on this thing, but it's got at least another 50 HP and better mileage and handling to boot. Only thing left now is to get a different set of front tires on to replace the Cooper Cobra's on it that refuse to balance. This is the last set of Cooper's I'll ever buy after a long 30+ year history of buying and running them. (but that's a whole 'nother story)