i have a 99 taco. i recently installed a 3" lift and 33" swampers. the stock gears are 4.10 and noticed a huge drop in gas mileage, i know the obvious answer to the question in hand. what do you guys sugest in a new gear, i do alot of driving so an extreme low gear is out of the question, but i do have a trd limit slip" i love it" any suggestions

 

4.56 is the only thing close. I am unsure about the facory 4.30, but I would just go the 4.56 route.

 

Have you been calulating for the difference in tire diameter when calculating mpg? If not it might not be as bad as you think.

 

You should recalibrate your speedo for your new tires.

 

which engine do you have? for 33s, 4.56 would be much better with either engine, and 4.88s would be best if you have a 4 cylinder

 

There is no way to recalibrate the speedo. BUT, you do have to adjust the miles to compensate for the error when you figure mileage. But your mileage also will be less because now the engine isn't in it's optimum range, it's "lugging" a bit.

4.88 gears. Trust me. With the bigger tires there is increased mechanical resistance and increased wind resistance (higher profile now.) While the math says 4.56, it doesn't account for those things. Going to 4.88 is perfect. I took this advice from someone who knew way back when I did my first gear swap (for 33s) and he was dead right. You will not regret it.

 

Yup, you have to compensate for the tire size difference in your mpg calculation.

 

Go with the 4.88s.I have factory 4.56s with 31s,and it is just right.

If I put on 33s I would need 4.88 to put it back to were it was a originally.

 

I got 33's on mine, and went with 4.88's. Wouldn't have gone another route. I did the math and 4.88's w/ 33's bring the speedo almost exactly back to stock in my case.

And like everyone else has said, you should consider the tire difference when calculating tire speed. Heres and example:

If stock size is 28" and you put 33" on it, then the % difference is roughly 18%
("final - "stock / "stock). That means you have traveled 18% more distance than what your odometer reads. Say you drove 327 miles. Take 327 times 1.18 (100% plus the 18%), which equals roughly 386 miles. That would be the actual mileage you have driven. Take that and divide it by the gallons and wham, there ya go.

(Someone correct me if im wrong with that example... its been a long day, and it could be wrong, i didn't look it up, thats off my head.)

 

Oh and look at axle ratios: (4.88-4.10)/4.88 = 19% (almost same as tire % diff.)

I think thats the skinny of it, When i did my truck i did the whole long calculation involving the trans, t-case, axles, RPM's, and tire diameter... This method simplifies it way more, and gets ya where you need.

 

Hey, you guys w/ the 3.slow and 4-bangers need to fess up.

3.4L on 33's to have decent highway mileage needs to have 4.56's

That will put him at the same RPM's as he'd get w/ 31's running on 4.30's

You can't compare that to what a 3.slow needs or what a 4cyl needs.

 

(33-31)/31 = ~6%
(4.56-4.30)/4.30 = ~6%

Theres your match back to factory

And mine is a 4cyl, so 4.88s were what i needed, not necessarily the same for a different truck.

 

my buddy has 4.88s in his tacoma with 35s and can tow a jet sled(river fishing boat) behind it, albeit huffing and puffing a little, but then again you're in the V8 range if you're gonna tow something like that

 

well i wasnt looking and the actual mile on the odometer, i just know how far i can go on a tank of gas... my one way to work every day is 40 miles, i know it is like a 1 hour drive one way, but i drive semi truck for pepsi in ohio, so i dont make all that bad of money. and after the tire change the odometer now said 30 miles one way , so iknow it is off. has anyone put a dakota digital speedo recalibrator on??? it is like $75.00 and what am i looking at on a cost for 4.56 in front and back??? ill install them i have done gear swaps before.

 

The speedo recalibrator, (if it works on yer Taco,) will not cure the problem. Change your gears - you won't regret it. Shop around - you should be able to get the gears installed for 1000 bucks all done. Much Less if you can carry in your third members. (I got mine done for $600 carry-in) DIY parts only around $400-500.

 

cool sounds like a plan. i hear 488 and 456, in all reality what is the gear i should run, i rairly offroad all that much, mostly on road, it is the2.7 4banger!! so 456 sounds good to me what do you all think? plus i saw an ad in the latest off road adventures mag and genuine gear has a complete set front and rear plus install kit for399.99 and your choice of 456, 488 and529

 

With the 2.7, definitely get the 4.88's. Oh yeah and watch what gears you get, search for my thread on My Bad Yukon Gears. They turned out ok after some hassle though.

 

There is a nice group of calculators for this stuff over at offroaders. http://www.offroaders.com/info/tech-...alculators.htm