Tire load sensitivity describes the behaviour of

tire A tire (American English) or tyre (British English) is a ring-shaped component that surrounds a wheel's rim to transfer a vehicle's load from the axle through the wheel to the ground and to provide traction on the surface over which t ...

s under load. Conventional pneumatic tires do not behave as classical friction theory would suggest. The load sensitivity of most real tires in their typical operating range is such that the

coefficient of friction Friction is the force resisting the relative motion of solid surfaces, fluid layers, and material elements sliding against each other. There are several types of friction: *Dry friction is a force that opposes the relative lateral motion of tw ...

decreases as the vertical load, Fz, increases. The maximum lateral force that can be developed does increase as the vertical load increases, but at a diminishing rate.

Behaviour

Coulomb

friction Friction is the force resisting the relative motion of solid surfaces, fluid layers, and material elements sliding (motion), sliding against each other. There are several types of friction: *Dry friction is a force that opposes the relative la ...

theory says that the maximum horizontal

force In physics, a force is an influence that can change the motion of an object. A force can cause an object with mass to change its velocity (e.g. moving from a state of rest), i.e., to accelerate. Force can also be described intuitively as a ...

developed should be proportional to the vertical load on the tire. In practice, the maximum horizontal force Fy that can be generated is proportional, roughly, to the vertical load Fz raised to the power of somewhere between 0.7 and 0.9, typically. Production car tires typically develop this maximum lateral force, or

cornering force Cornering force or side force is the lateral (i.e., parallel to wheel axis) force produced by a vehicle tire during cornering. Cornering force is generated by tire slip and is proportional to slip angle at low slip angles. The rate at whi ...

, at a

slip angle In vehicle dynamics, slip angle or sideslip angle is the angle between the direction in which a wheel is pointing and the direction in which it is actually traveling (i.e., the angle between the forward velocity vector v_x and the vector s ...

of 6-10 degrees, although this angle increases as the vertical load on the tire increases. Formula 1 car tires may reach a peak side force at 3 degrees Wright P., 2001, "Formula 1 Technology",

Society of Automotive Engineers SAE International, formerly named the Society of Automotive Engineers, is a United States-based, globally active professional association and standards developing organization for engineering professionals in various industries. SAE Internatio ...

(SAE) Warrendale, PA.

Example

As an example, here is data extracted from Milliken and Milliken's "Race Car Vehicle Dynamics", figure 2.9: The same sensitivity is typically seen in the longitudinal forces, and combined lateral and longitudinal slip.

References

{{Tires, state=collapsed Tires Motorcycle dynamics

Behaviour

Example

See also

References