4.3 regear for AT thread

He put oversized tires on ...so ??? Needs the math for that.

 

It can help mpg as the engine no longer has to work as hard to get the vehicle to speed. He effectively lowered his gearing and also added some weight that the engine now has to work harder to overcome, but using more fuel. The extra gearing from a regear will allow the engine to relax a bit, using less fuel.

 

Two important truths of the universe:

1: you don’t get something for nothing.....ever, not ever, never.

2: guys on Tacoma World will always exaggerate their fuel economy numbers after lifting and larger tires.

 

Lol Amen

 

True. I can vouch for Weirich tho since he's my roommate. His averages 19 mpg on the highway when I've borrowed it. The taco box truck up at Marlin Crawler was getting 17 mpg on the highway and he's on 40s. Gearing and recalibration are huge.

 

Just as another data point, the best tank I ever got was just a touch over 25 mpg, and that was using a bunch of hypermiling tricks. My typical fuel economy is 23+ unless I tow a lot. My typical commute allows me to drive between 45 and 60 mph most of the time.

Bone stock, manual transmission, but I do run the tires a bit fuller than typical, between 45 and 50 psi. No, I don't have treadwear problems.

If I don't limit the speed, and don't limit the acceleration from a stop, and don't coast up to stops as much as possible, the fuel economy drops to 18-19. It only has 8,500 or so miles on it.

On the highway at >/= 70 mph, the aerodynamic drag becomes the overwhelming factor and F/E drops to 19'ish.

 

ouch, I have 285/70/17 with 3in lift and averaged ~17mpg from Florida-Tennessee (1800 miles round trip going 70-75mph). In Florida driving around town keeping it slow I average 16mpgs. No tsb or ov tuning yet

my factory tire was a 265/65/17 and i would average 18 around town and ~20mpgs on florida flat highway roads

I would like to go up in tire size and gearing

 

Did you use the hypertech tool to correct your speedo? If not, that is why your MPG's are reading so low.

The stock calculations are very generous on stock tires. I was getting 23-24 on avg and that seemed rather high. Went to a 265/70/17 and my mileage is about 20 per the computer. Over the last month i've done the check manually and been almost spot on with the cluster reading at 20.

Your actual mileage likely isn't as bad as being displayed. Don't regear just to improve mileage, do it for a performance benefit.

Read through the 4.88 thread. 4.88's for the auto still put your overdrive gears lower than the manual guys with 4.30's.

My 4.88's are being installed this weekend.

 

And 5.29s on an AT have almost the exact same final drive ratios for 5th and 6th gear as the MTs on 4.30

 

'17 DCSB on 285/75R16s with 4.88s gets 19.5mpg on Houston freeways. Get it out on the open road, especially in wind, and that will drop to as low as 14.5 at 80 mph.