Grip

What Is Grip?

Grip is a consequence of molecular contact that can be measured to an incredibly small degree – about one hundredth of a micron – and is amplified when a car slides. Grip is created by molecular interaction at the point of contact between a tyre and the track. When the tyre is moving, part of the tread is physically touching the surface at a given point, and its molecules extend until contact is broken.

How Tyre Grip Is Generated

Tyre grip is generated by two mechanisms, sometimes referred to as physical grip and chemical grip. The first process involves the shear deformation of the contact patch, while the second involves the coefficient of friction of the tyre. The internal stress response to shear deformation depends upon the shear modulus of the tyre, which is temperature-dependent. The friction coefficient is dependent on both tyre temperature and slip velocity. Both mechanisms by which grip is generated are therefore temperature-dependent.

Grip Defined

Grip can be described as the amount of traction a car can transfer to the track through contact between the tyres and the road surface, affecting how easily the driver can maintain control through corners, during braking, or under acceleration. Grip depends on track condition, the temperature of the track and tyres, the tyre compound in use, and the car’s overall set-up. Available grip is a finite value for any given part of the track.

Track Evolution and Tyre Temperature

F1 drivers commonly remark during Friday free practice that track conditions (or grip) are not ideal, or that later in the session conditions will improve. This means that grip will increase as more rubber is laid down on the track and dust, sand, and dirt are cleared from the surface by passing cars.

Same is valid when they say that they can’t get the tyres to work properly or can’t get proper temperature to the tyres. All that means: “I don’t have enough grip.”

Factors Affecting Grip

Grip also depends, as I said before, on the quality of the overall car set-up: aerodynamic efficiency, aerodynamic grip, mechanical balance, brake balance, downforce, dynamic weight distribution, ride height, suspension set-up, and the combination of all these elements. A lot to think about for a race engineer and driver.

For more on how tyres create grip, read here.