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Tire load sensitivity describes the behaviour of
Tire load sensitivity describes the behaviour of tire
A tire (North American English) or tyre (Commonwealth English) is a ring-shaped component that surrounds a Rim (wheel), wheel's rim to transfer a vehicle's load from the axle through the wheel to the ground and to provide Traction (engineeri ...
s under load. Conventional pneumatic tires
A tire (North American English) or tyre (Commonwealth 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 w ...
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. Types of friction include dry, fluid, lubricated, skin, and internal -- an incomplete list. The study of t ...
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
Coulombfriction
Friction is the force resisting the relative motion of solid surfaces, fluid layers, and material elements sliding against each other. Types of friction include dry, fluid, lubricated, skin, and internal -- an incomplete list. The study of t ...
theory says that the maximum horizontal force
In physics, a force is an influence that can cause an Physical object, object to change its velocity unless counterbalanced by other forces. In mechanics, force makes ideas like 'pushing' or 'pulling' mathematically precise. Because the Magnitu ...
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 wh ...
, 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 su ...
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 is a global professional association and standards organization based in Warrendale, Pennsylvania, United States. Formerly the Society of Automotive Engineers, the organization adopted its current name in 2006 to reflect bot ...
(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.See also
*Racing slick
A racing slick or slick tyre is a type of tyre that has a smooth tread used mostly in auto racing. The first production slick tyre was developed by M&H Tires in the early 1950s for use in drag racing. By eliminating any grooves cut into the tre ...
* Weight transfer and load transfer
References
{{Tires, state=collapsed Tires Motorcycle dynamics