Great posts all! I just have a little to add, I put some bigger tires on my truck, 315/70R17's and I did notice a difference in mileage, I expected mileage to go down overall, but I drive a lot between 45 and 75mph and while there wasnt a large bump, it was noticable :). I also enjoy the look, I put a 3" block in the front so my truck is a little "over leveled"(2" would make it level), but I love the look and the tires seem to fill the void quite nicely. I have some pics posted on my profile here but if you want to see any specific areas I can go take a pic for ya :).
I did notice a large difference in off the line performance, and I use more gas to go, but once I am up to speed I didnt notice any difference. I have 3.73 gears btw, and if anyone wants to donate to me to put 4.10's or 4.56's in feel free! :smiley_roll1::hehe:

Thanks for the great replys everyone. Its really given me a lot to think about. I'll see about getting some time at the local track come spring and then do some math. The vac gauge sounds a lot like a manifold pressure gauge from an airplane. I'm a commercial pilot by trade, and on many light aircraft you use a combination of manifold pressure(actually manifold suction), engine rpm, and fuel air mixture controls to set power. I have an aircraft mechanic friend that may have an old manifold pressure guage around that cant be used in an aircraft anymore. It would be pretty simple to plumb it in. As for trips to cabelas, I'm sorry to say we dont have one around here yet, but we do have a bass pro shop a couple hours away. I've found my fuel economy is usually better on the way there than it is coming home. I have attributed this to an increase in vehicle weight on the return trip as a result of exchaning light portable money for heavier items like guns and fishing gear.

Thanks again guys

Joe

That sounds like the exact same guage so it should work. The guage I use measures manifold "pressure". You'll need one that only reads to about 25-35 inches of Hg. Regular driving I see 20" on idle, 25" if there is a bit of engine braking. Probably will be the same exact guage and your already trained to use one.

Ah, the joys of recips. :throwup: Throttle, mixture, prop - and all for just ONE engine! (Too damned many levers in my opinion.)

As for your mileage to and from the shop, I suspect it is "downhill" from you. You could confirm this with a GPS that shows elevation.

- Jack

Are you a pilot too Jack?

Yes, I am, Joe. about 4600 hours in the Air Force. Part of that time was as a Forward Air Controller flying O-2s. (The Air Force's version of the Cessna 310 I think? It was about 30 years ago now and it's hard to remember.)

Anyway, the damned plane had a huge, heavy radio pallet in it that overloaded it to the point that if you lost the rear engine, the front one was only good enough to take you to the crash site. We didn't even wear parachutes, because we were usually too low anyway and the extra 30 pounds might make the difference between getting to a good landing site or not.

- Jack