I have a 1990 toyota pickup 22re 5 speed with stock trans, 31's, and 4.56 gears. The truck has great acceleration and can hold 55mph on hills but i need better fuel mileage. Thinking of going with 4:10 or should i go lower?
At 18mpg highway now....

 

how about another set of tires and wheels that is smaller than your current ones...

 

4.10 is a higher gearing than 4.56...not lower. and i agree with Idivinag. also remember, your driving a toyota pickup, not a prius, you can only get so good. i would be happy you get 18. but if you really need better milage try a tune up, seafoam, and smaller tires.

 

:dom o:: sickle:


As you can see from the results listed in the graph above that 4.56 is great gearing for what your doing. And yes smaller tires is about the only thing you can do to improve. Or buy a car. If you go with higher gears such as 4.11's you will actually lose mpg.

After all we dont log the rain forest, we just move to the dessert instead.

 

It's not pretty but you can keep the same ride height and tire size and get better mileage with a low profile tire. Doubtfull you will save money short term since you'll need to pay for a bigger set of rims and low side profile tires.

Going to a smaller gear effectivly increases your tire size, like mentioned, this will make you push more pedal to accelerate at your choosen rate. If your acceleration isn't happening at peak torque you're basicly wasting fuel.

Bigger tire = higher top speed, and more effort to accelerate
Smaller tire = higher torque, and less effort to reach top speed.

You could wax 'er up and load a couple sand bags in the back, then it'll look like it's going faster. Just lay off the skinny pedal and take abit longer to accelerate, it does wonders.

 

I know many will disagree, but you always get best economy at the lowest RPM for any given speed. If you go with a smaller tire, your revs will be higher obviously. More RPMs usually equals more fuel, all other things equal. (I realize you aren't using less fuel if your foot it bottomed to the floor to maintain speed)

MOST of your economy depends on how you drive. Learn to "DWB" (driving without brakes), do not idle or limit it as much as is safe, time stoplight and start braking way ahead of time, moderate takeoffs, and just go slower.

Personally I think you are doing fine. I don't think you'll be happy with your 31s and 4.10s. You'll likely have to gear up to hold speed and that wastes fuel. I would try to focus on your driving techniques. Specifically idling- it just kills any good mileage numbers you build up to.

 

Here are some follow up questions, and information to help you decide.

What engine speed are you normally cruising at? If it is between peak torque and peak hp, your doing about the best you can be. If it is over peak HP you might do better with a bigger tire(smaller gear).

In addition to vasinvictor's post:

As long as your idle is properly set you're not really wasting that much gas. I always idle/warm-up while I smoke a whole cig at minimum, I get 20+ but mine is also a 2wd so there is the weight difference.

Remeber it takes more fuel to restart than it does to idle as a general rule, so don't shut off for lights or short stops. You might be in a "no-puffer" area, so might get a ticket for idling but it's a pollution issue not wasting fuel

DWB means coasting into lights not braking early. Dropping your speed to coast upto a light is about not having to accelerate from a dead stop.

Accelerate slow and just smile when the twits gun it around you and you wind up stopped behind them at the next light. "Yeah thats right that just cost you a buck to pass me, ha!"


of course don't forget your full tune ups, and make sure your tires are aired to the limit!

 

Ok from the sounds of it I just need to change my driving style. Thanks for all the input. The thing that sucks is I had a 1995 truck (totaled) with the same setup and was getting 24mph???

 

Full tune up with good spark plugs, maybe something in the exhaust or the oxygen sensor is due for a replacment. And remeber tire pressure is a big deal, could just be a difference in tire brand or manufacturer variations. Or too much junk in the trunk.

 

if you really want better, do as others say and go with some 235/75/15 highway tires