Abstract: An apparatus is disclosed for testing the traction properties of pneumatic tires. A frame is provided having a plurality of structural members. A suspension system having upper and lower arms each having first and second ends is rotatably attached to the frame at the first ends of the upper and lower arms. A hub assembly having a triaxial force transducer mounted therein is attached to the second ends of the suspension system by means of a pair of spherical bearings. An aperture extending through a rear wall of the hub assembly, through the triaxial force transducer and through a front wall of the hub assembly supports a driven axle for applying driving or restraining torque to a pneumatic tire mounted on the front surface of the hub assembly.