A method of detecting the presence of an undersized, e.g., mini-spare, or an underinflated, oversized or overinflated tire or tires on a passenger motor vehicle improves operation of traction control, stability and anti-lock brake systems by compensating for such operating anomalies. The method includes the steps of sensing the steering angle, sensing the actual rotational speeds of each wheel, determining the actual vehicle speed, calculating each expected wheel speed based upon the sensed steering angle and wheel speeds, calculating each tire diameter based upon the calculated wheel speeds and, finally, determining whether such diameters are within various defined ranges which permit normal operation, permit reduced function operation, or require system shut down.