Minimum tread depth on every groove on all tires must be at least _________.

Tires:
Make sure you have enough tread on your tires. The drive tires must provide traction to push the rig over wet pavement and through the snow. The steering tires must have traction to steer the vehicle. Enough tread is especially important in winter conditions.
You must have at least 4/32 inch tread depth in every major groove on front tires and at least 2/32 inch on other tires. More is better. Use a gauge to determine if you have enough tread for safe driving.