Vehicle tire load estimation

A load estimation system and method for estimating a vehicle load is disclosed. The system comprises at least one tire (12) supporting a vehicle (72); a tire rotation counter for generating a rotation count (22) from rotation of the tire (12); a distance measuring means for measuring a distance travelled (38) by the vehicle (72); an effective radius calculating means for calculating effective radius (r eff ) of the tire (12) from the distance travelled (38) and the rotation count (22); and load estimation means for calculating the load (34) carried by the tire (12) from the effective radius (r eff ).