A machine for measuring force variation or imbalance of tires particularly at high speeds. A rotating roadwheel is engaged by a tire mounted on a spindle. Force sensing means, such as load cells, are operably interposed between the tire spindle and a force sensor mount. To minimize the adverse effects of mechanical resonance of the machine on force measurement accuracy, the roadwheel and/or the force sensor mount are connected to ground through dampers which provide a damping ratio of at least about five percent and preferably higher. Where the force sensor mount is to be supported by such damping means, the invention further contemplates interposing a large mass between that damping means and the force sensor mount.