When a tire is inflated and loaded, it deflects. After the load is removed, it returns to original shape. The behavior of the tire without rotating is called "Static Characteristics".

<Vertical deflection> Linear distance between the section height of the unloaded tire and the loaded tire.
<Spring rate> As load increases, so does deflection and as inflation increases, deflection decreases. Spring rate=Load/Deflection (Kg/mm)
<Static Loaded Radius> When a tire is deflected, the radius is called "Static Loaded Radius". See size designation. Spring rate is higher in bias tire than in radial, which means radial tire deflects more because of thinner sidewall.

When a tire is inflated and loaded, it deflects. After the load is removed, it returns to original shape. The behavior of the tire without rotating is called "Static Characteristics".

<Vertical deflection> Linear distance between the section height of the unloaded tire and the loaded tire.
<Spring rate> As load increases, so does deflection and as inflation increases, deflection decreases. Spring rate=Load/Deflection (Kg/mm)
<Static Loaded Radius> When a tire is deflected, the radius is called "Static Loaded Radius". See size designation. Spring rate is higher in bias tire than in radial, which means radial tire deflects more because of thinner sidewall.

Then a tire is rotated, behavior of the tire without rotating is called "Dynamic Characteristics".

<Rolling Radius>
When a tire is loaded and rotated, the distance made by one rotation divided by π is called "Rolling Radius", which stands for the actual radius at certain speed.
 

Revolution per mile is calculated by; =1609344/(2π*Rolling Radius) =1609344/Distance of a rotation (in mm)

<Rolling Resistance> When a vehicle runs, the engine's power will be consumed by the following resistance. *Aerodynamic Resistance *Tire Rolling Resistance *Power train & Mechanical Resistance In addition, acceleration and uphill resist-ance will also consume power, if applicable. Rolling resistance consists mostly of energy loss due to flexing movement while rotating. Rolling resistance is affected by greatly by vehicle speed as well as inflation pressure. Therefore speed reduction and proper inflation pressure is quite effective way to save fuel trucking company.

<Cornering force>

When a tire is turning with a slip angle, contact patch of tread is deformed by centrifugal force from the road. Then tread tries to return to original shape. Specifically contact patch works like spring. The vehicle receives the reaction force in the opposite direction of deformation, i.e. if a tire steered left, the vehicle receives the force in the opposite direction and turns to left.

<Tire wear> When an inflated and loaded tire, which is free rolling, enters the contact patch, the contact patch changes to the road surface, which means that the tread is forced to shrink in both radial and tangential direction. The tread slips when it returns to original profile and the slip causes a tire to wear. Therefore flat or stiff tread can give longer tread life as well as deep or wide.