would i get better gas mileage if i were to put my 34" tires back on my 20"s? my setup is a 4.olsohc with 3.73 rear..gas mileage isnt a problem but i didnt know if it would get better because of the more rotating mass = less rpms?

 

Get better at highway speeds and lower in the city. I noticed a change on the highway when I regeared. Ended up getting worse.

 

dont forget that youre turning much more weight and low rpms doesnt always mean good millage.

 

It really comes down to "load". If the load is higher.. your throttle positionwil get greater and the timing will drop. That will hurt.

Thats exactly what happened to me going from stock to 32s. I've now got the tune adjusted so that my mileage is where it used to be. But its running a butt load of timing on 93 octane to do it.

Rich

 

There's a fine line between 'better' and 'worse'. with 3.73's and 34's...even though you are spinning less rpms, you are putting more of a load on the engine, thus creating larger fuel consumption. at highway speeds...the motor is working so hard to keep the darn thing moving that you lose any and all 'gains' you might have got. reason being, is that the rpms drop so much, that you are out of your powerband where the torque output at highway speeds have been lowered, and it's harder for the truck to 'keep speed'.



4.0L sohc + 3.73 + 35's = massive suckage of fuel and drivability.

my truck with the 4.0L sohc, 35's, and 4.10s was fine in the fuel department...but the truck completely sucked on freeway runs. the darn thing wouldn't 'keep speed' on the highway...no torque at all in 5th gear and going 65.

 

I really like my 31's and 3.73 with the sohc. Didn't lose much 'jump' for city driving, and I can still pull 20-22mpg on the freeway no prob.

 

ohv baby