Less than a millisecond! That is how much time the tire has to hold you to the road.
The tire plays an essential role in safety. He has to provide sufficient grip when turning and braking on both dry and wet roads. Grip is ensured by the contact area between the tire and the road, on a tiny patch no bigger than your hand.
Between the rigid road and the plastic elastic rubber, two factors come into play: molecular adhesion and indentation.
On dry ground, rubber has a tendency to stick, accounting for 20% of grip.
Rubber's malleability helps it to distore the impact of road surface irregularities. This is indentation and accounts for 80% of grip.
On wet roads, water molecules neutralize the grip effect of tires, leading to increased braking distances, in extreme cases hydroplaning. When this happens, the challenge for the tire is to drain the water away in order to reestablish its dry contact with the road. How? Firstly, tires are designed to form a rounded footprint to drain the water away. Secondly, grooves between the tread blocks form channels in which the water can be temporarily stored or else drained away to the rear. Lastly, sipes in the tread block act like claws, with their edges cutting through the film of residual water to ensure the rubber is in contact with the ground.
Find out more about winter tires
On winter roads (wet, icy, snowy and cold roads) all parts of the tire work together for optimum grip:
• The tread pattern for a Caterpillar or Cog effect: an incised directional tread pattern, special blocks of rubber and a high void ratio level give the tire better grip in snow.
• Siping for a claw effect: bigger, more complex-shaped sipes act like thousands of small claws which attach themselves to the ground.
• Sipe density for surface grip: the greater the rubber area of rubber on the ground, the better the grip. This principle is extremely useful on icy ground.
• Rubber compounds for a material effect: the rubber must remain supple and efficient at temperatures below 7°C.
Remember: In addition to these factors, the road surface also has a significant influence on grip.