Abstract: A method and apparatus for reducing tangential force variation in a pneumatic tire wherein the tire is mounted on a wheel rim, inflated to operating pressure, and rotated under a predetermined load against a loading drum. Force transducers on the axis of the loading drum measure the tangential force variation as the tire rotates. These measurements are placed into the memory of a computer. The computer processes this data to obtain the magnitude of the tangential force variation and the phase angle from an arbitrary location of the variation or the angular displacement to the point of maximum magnitude. The computer outputs a V-shaped ramp voltage level signal for controlling the servo-valve which moves a rotary grinder into grinding engagement with the inner tread ribs of the tire. The grinding is repeated for a number of revolutions depending upon the magnitude of the variation.

Abstract: A method and apparatus for reducing tangential force variation in a pneumatic tire wherein the tire is mounted on a wheel rim, inflated to operating pressure, and rotated under a predetermined load against a loading drum. Force transducers on the axis of the loading drum measure the tangential force variation as the tire rotates. These measurements are placed into the memory of a computer. The computer processes this data to obtain the magnitude of the tangential force variation and the phase angle from an arbitrary location of the variation or the angular displacement to the point of maximum magnitude. The computer outputs a V-shaped ramp voltage level signal for controlling the servo-valve which moves a rotary grinder into grinding engagement with the inner tread ribs of the tire. The grinding is repeated for a number of revolutions depending upon the magnitude of the variation.

Abstract: A method and apparatus for reducing lateral force variations and overturning moment variations in pneumatic tires by detecting the magnitude, direction and location of such variations and alternatingly grinding off opposite portions of the two shoulders of the tire tread. A tire is mounted on a test rim, inflated to operating pressure, and rotated under a normal service load against a loading drum. Force variations in the lateral and radial directions are detected and measured by load cells operatively associated with the drum axle and located at opposite ends of the axle. The sum of the lateral force variation forces or the difference of the radial force variation forces measured by the load cells provides a voltage level signal representative of the direction, magnitude and location of the lateral force variation and the overturning moment variation. The phase angle of this signal is ascertained to determine the location on the tire of these variations.