A tire testing machine (10) comprising a movable simulated road surface (14), an axle (16) including a bearing surface (22) around which a tire/wheel assembly (T) can rotate; and a frame (18) which supports the axle (16) in a non-rotatable but vertically floatable manner relative to the simulated road surface (14) whereby the tire/wheel assembly (T) can be loaded in rolling engagement against the simulated road surface (14). The frame (18) comprises tie members (26) which extend from the axle (16) to a stationary support (28) in a geometrically sturdy (e.g., triangular) arrangement and non-damping piston members (30) which are interposed between the tie members (26) and the stationary support (28). The geometrically sturdy arrangement of the tie members (26) can be an isosceles triangular arrangement and the simulated road surface (14) can comprise the outer circumferential surface of a road wheel (20).