Gearing

[Iltoys]

Running 35/12.5/20 amp tires and on the highway it's not hitting 8 gear very often with the 3.21 gears. Changing the gears out isn't an options for my wallet and wondering if there is anythi g I can do like a programmer to help the issue or anythi g at all.

If not I'm ok with it for the amount of highway I do

 

[stevj]

When you changed your tires from the stock 32" diameter to 35" diameter, its the same as if you had kept the stock 32" tires and changed your rear end ratio from 3.21 to about 2.93. About 8.5 to 9%, if my math is right.
That means your engine rpm at speed is much lower than it would normally be (about 100RPM/1000RPM), and being further from torque peak RPM, is under more load than if things were stock. Higher engine load means delayed upshifts, slower acceleration and increased fuel usage.
If transmission gear at highway speeds is a concern, you can return to stock tire size, or use manual shift mode and set maximum transmission gear to keep engine in RPM range you prefer. I'd recommend 7th.
Driving around the Pacific Northwest, I haven't noticed much difference in MPG between 7th and 8th gears. I have stock tires and 3.9 gears, and I use 7th most of the time.

Steve

 

[brian42]

Tuning might help but that requires an unlocked PCM in addition to the tuning. You mentioned that the gear swap was not in your budget so the tuning is not going to be an option as that is going to run you more than new gears.

You can get smaller tires, lighter tires, or hard compound (high mileage) tires. Changing the weight and resistance/friction might help but it might not.

Outside of downsizing your tires there's no other guaranteed cost-effective improvement for your current situation.