Radial Force Variations

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The Radial Force Is A Force That Compresses A Tyre. Based On Its Size, A Tyre Has Softer (-Item A- ) And More Rigid Zones (-Item B- ) Due To Constructive And Production-Related Factors. Given This, The Tyre Compresses To Various Extents At A Constant Wheel Load (-Arrow 1- ) And A Constant Tyre Pressure (-Arrows 2- ). This Varying Spring Action (-X- ) In The Tyre Can Cause Vibrations In The Chassis On Even Road Surfaces And The Driver May Notice This As Shaking In The Steering Wheel, For Example. Measuring The Radial Force Variation Involves Running The Tyre On A Wheel Balancing Machine That Measures Radial Force Variation While Applying A Constant Load To The Tyre. This Simulates The Rolling Of The Tyre On A Driving Surface. Variations In Radial Force Occur Independently Of The Direction Of Rotation Of The Tyre And Are Measured As The Difference Between The Maximum And Minimum Radial Force ("Peak-To-Peak" Value).

Fig 1: Checking Tire Radial Force Variations

Courtesy of PORSCHE CARS NORTH AMERICA, INC.