Abstract: A system for distributing road surface information comprising means for sensing numerical information on slipperiness of a road surface; means for sensing positional information of the travelling vehicle; means for transmitting the numerical information and/or positional information from the vehicle; means for collecting the information transmitted by a plurality of vehicles; means for preparing road surface information of a road on the basis of each information; means for distributing the road surface information also to a vehicle other than the vehicle; and means for receiving the distributed road surface information. By changing a parameter of road surface information in a vehicle movement control system such as an ABS or a VSC, the performance of the control can be improved.

Abstract: An apparatus for presuming a condition of road surface comprising: rotational speed detecting means for periodically detecting rotational speeds of four tires of a vehicle; first computing means for computing a slip ratio from measurement values of the rotational speed detecting means; second computing means for obtaining a relational formula between the slip ratio and acceleration/deceleration of the vehicle; and friction coefficient judging means for judging a coefficient of friction occurring between a road and a tire on the basis of a slope of the relational formula obtained by the second computing means. The road friction coefficient &mgr; can be judged with high accuracy in short time by using only the wheel rotational speed information of four wheels. Thus, the performance and safety of a vehicle can be increased.