WheelCollider Grip

Hi !

I've been working on a car physics/control project and I faced a problem when adding torque to the wheels, with small values of torque the wheel move perfectly without loosing grip and spinning, but it accelerates too slow and the top speed is low, so i decided to give it higher values, the vehicle still accelerates slow because the wheels at start loose grip and spin, but the vehicle reach higher top speeds with higher torque, so i would like the wheel to have a higher grip, but i didn't find a proper function to it, tried to use Forward friction but didn't change anything in the vehicle's grip or maybe I didn't know how to use it, I need a solution for this no matter how difficult it is.

Thank you.

A part of the control script that adds torque :

 WheelColZ[2].motorTorque = TorqueValue;
 WheelColZ[3].motorTorque = TorqueValue;