I have a set of 315 70's on the truck and my mileage did suffer from them, but heres the question. Do yall think my mileage will go up any if I took off the 315's amd put 285 70's on it instead?

 

What pressure are you running in the tires? Obviously running them at higher pressure will help. Do you have spacers in the front? Keeping you speed down is probably the best thing you can do to improve your fuel mileage. Just out of curiousity what are you seeing for fuel mileage right now?

 

Yea im just put in 2" spacers in the front friday and I'm running 50 psi in all tires. I also drive like a grandpa every where I go.

 

To tell you the truth I dont really knoe for sure what I'm seeing for mileage right know because I just put the edge on and the intake manifold on.

 

I went from 315s to 285s back in my 03 and I saw no difference in mileage. I have seen others post that their mileage went up though. You never know until you do it I guess.

 

I see you have the Edge mileage max installed. Did that help any?

 

When I went from the stock 265's to 315, I lost a little less then 1MPG.
I'd assume going to a 285, you'd gain maybe .5

 

Yea the edge helped a little but I just put it in so I'm not real sure of the mileage gains yet.

 

I would add more air to your front tires like no less then 65 psi in the front and 50-55 read when empty. IMHO 50 psi is way to low for the front tires.

 

Okay, I'm confused.....

If the 315's are taller, that should lower your RPM going down the road and increase your mileage,,, Problem is with taller tires your odometer will read that you went less mileage than with the shorter tires, so it might calculate that your mileage is lower. Boy, doesn't that help.

The only way to really calculate it would be with a GPS based mileage system.

 

This is more confusing than I thought it would be!

 

Use a stop watch and mile post to calculat MPH. Take the time it takes to travel from one mile post to another at a certain speed and then devide it by 3600. For those of you that may not know. lol. 48 seconds to go from mile post to mile post. 3600/48= 75mph. If you don't want to use a GPS or don't have one.

 

Well the taller tires should help, but the front of his truck sits up in the airstream more, and the added rolling friction of the wider tire all add to help negate the good effects the taller tires would have. You would be surprised how much added resistance a truck will have by being 3 inches higher, especially at highway speeds. Yet another reason the 4x2s have an advantage on fuel mileage, their front ends sit down nice and low.

 

Also taller tires can hurt your mpg if you do a lot of stop and go city driving.

 

Doesn't the larger tires take more energy to turn b/c they have a larger foot print and they are a heavier tire?