2016 Tacoma with 4.88 gears and 33 tires and Hypertech

Uncheck the box for gears and get the actual size in inches for the stock tires and your new ones. You should be able to find that relatively easily on both manufacturers website.

 

Ok I will try that and see but I think I have already tried it and was still off

 

For the new tires, I'd highly suggest getting a real measurement with the tire raised off the ground. The specs listed on the manufacturer websites are almost always inaccurate (by as much as an inch).

After that, fine tune the size setting using GPS speed as the reference.

 

Although this is an older thread here are my comments:
I have 33's and 5.29 gears. My hypertech is only set for the tire size. No gear information is added. I first added the approximate tire size, measured by wrapping a string around teh tire for teh circumference to get the diameter. Then using a Garmin GPS that I have mounted in my truck I drove the interstate and side roads to compare the speedometer and the actual speed. I adjusted the tire size up or down to the 100th of a decimal. Doing this I dialed in the correct tire size to enter so my speedometer is now deadnuts on to within a tenth of a mph. It has maintained this accuracy and it is confirmed by both my GPS and roadside speed signs. In the Tacoma a gear ratio setting is not required in the hypertech as it has no impact on teh instrument cluster.