I began driving my 5 speed TJ shifting at 3k.

I recently upped my shifting to 3500 to see if I could punch out a little more accelleration (and it actually DOES seem to work..)

Now my question is, is it better on my gas miliage to shift earlier or later?

I can see it going both ways, earlier and the engine isnt as high into RPMs but I have to push the pedal down farther to get going again

Later and I wont have to push it to the floor, but my RPM is a little high...

Can anyone anwser??

Definitely Worse.

3500 is bout where I would think of shifting a 4 banger.. With the larger engine bout 3 grand would be good for me..
I would be thinking of the NEXT gear and the rpm when that gear starts pulling. I would not want the next gear lugging for lack of torque curve..
Specially true with larger than stock tires..
Big Jim <img src="/forums/images/graemlins/pfft.gif" alt="" />

I do have larger tires.

Will where I shift it really matter in the long run? Like will the gas miliage hurt it that badly?

The shifting at 3000 or 3500 isn't going to make any noticable difference in itself, what will make a diference is your style of driving. When you say "punch out a little more accelleration" That tells me you are not driving in a fuel saving manner. To save gas you should make gentle starts and smoothly, using as little pedal as possible, accelerate up to 3000, 3500 or what ever, you should also use the brakes less, the energy used to make your brakes hot comes from burning gasoline. So, slow gentle starts, slow speed and slow easy stops is the way to get the best mileage, If you don't want to drive like that, don't worry about it, shift wherever you want you'll get what you get. A SWB Jeep is probably one of the least efficient designs on the road. <img src="/forums/images/graemlins/cheers.gif" alt="" />

With larger tires your milage will suffer...period! I'd drive it (with larger tires) to keep the rpm up.
Big Jim <img src="/forums/images/graemlins/pfft.gif" alt="" />

Nice Forum!!

My first post and already causing trouble. <img src="/forums/images/graemlins/nana.gif" alt="" />

In most cases, higher rpm means more air/fuel going through the engine.... less mileage. The primary reason for overdrive is to lower rpm for better mileage.

ANd it's the width and more agressive tread design that kills mileage, not the diameter of the tire. Also the gearing because of larger tires on same axles may be wrong for engine, but not always... and you need to re-gear speedometer/odometer for the change or it will show less miles then you are actually driving.

Use bicycles for an example. Fat knobby tires are harder to pedal then narrow smooth ones.

I'm running 32s on 3.73s and get good mileage (20-21mpg on highway tread, but 19-20mpg on MTs), but probably wouldn't work on 3.55s.

Good Luck! <img src="/forums/images/graemlins/cheers.gif" alt="" />