As the tyres are the only part of your vehicle that grips the road, the depth of tread on them is very important for the safety of your vehicle.
Tyre wear (the depth of tread) signals the health of your tyre. Driving with low tread depth increases the potential for tyre failure and aquaplaning. Low tread depth in winter weather conditions can severely reduce grip and control.
Motorists driving with tyres under the legal limit also risk a fine.