I don't understand why I'm getting such awful mileage.

No doubt on that one. A truck with large tires, if they haven't had their odometer recalibrated, definitely has more miles that the ODO says.

 

But in order to recalibrate the odometer, you would have to re-gear correct?

 

Regear does not recalibrate. Bigger tires will always throw off odometer independent of regear, assuming your odometer is driven off of the rear and not the transmission, which apparently tacomas go off the rear.

With a scangauge you can calibrate for the tires.

 

And now I know why a scanguage is useful. Learn something new everyday haha

 

Only lifted trucks with bigger than stock tires, lift has nothing to do with it. There is no counterpoint, it is a fact that larger tires will throw off the odometer.

 

Wow, best i've gotten in my llifted v6 with stock tires 21-23mpg on highway. The oil'ed filters are nice BUT the oil can actually make your air more dirty than stock, not to mention performance doesn't always equal fuel gain. To the OP those mt's are heavy, and if you have aftermarket wheels then weight can be a lot more total then you expect. Calibrate your scanguage to get accurate readings. Seafoam, plugs, fluids, and watch your takeoffs from a stop, getting up to speed will use more gas as apposed to keeping speed. Fyi most cai's sacrifice some filtering percentage from stock to increase airflow. Change diff fluid, make sure your wheel bearings are good. Clean maf, tb is optional i cleaned mine at 87k and it was only a little bit of brown deposit, my tercel is another story, carbon was caked on. Add a can of seafoam to 1/2 the tank. 1qt atf fluid to oil drive 100 miles and then change oil and filter. U can use cheap dyno oil to use with this change. Just remember to change the filter.

 

how do you calibrate the scangauge for tire size? I havent seen that option. Is it the MPH option? Will that adjust the MPG too?

 

When I try, I can get 19-21mpg on long road trips. Otherwise I average around 16.5.

 

Go to More>Setup>Speed and adjust using gps or mile markers until it is accurate, it's all in the manual.