A drive up a hill

Hi. I’m developing a system to drive up hills with low gear but no progress. Increasing the motorTorque speeds up the vehicle, but is there any way to adjust the force the tire pushes against the ground?
wheel collider:

gear script:
car.torque = 1 / car.gearRatio;
car.torque will multiply to the rpm.
tireTorque(bengine.currentRPM / 6.3f * torque);
my car is Front-wheel-drive, and it will transmission power to front two wheel :))))