Off-Road Challenge cheats and cheat codes for Nintendo 64

Go to the track selection screen and press the following buttons or
button combinations. If the codes are accepted, you should hear a
sound of an air wrench.

Unlock Guadalupe track
Hold Down and hit R. After, highlight the Vegas track, h
old Z and press the gas.

Unlock Flagstaff track
Hold Left and hit L. After, highlight the Mojave track,
hold Z and press the gas.

Unlock El Cajon track
Hold Up and hit L + R. After, highlight the El Paso track,
hold Z and press the gas.

Unlock extra trucks
Go to the vehicle selection screen and press the following buttons:

Truck - Button
4x4 Monster - C-Up
The Crusher - C-Right
Punisher - C-Down
Thunderbolt - C-Left