charges occurs as described in the background of the invention at a respective contact region 42 of each tire 22 hereinbelow it is assumed that positive charges are created on tire 22 and negative charges are created on surface 28 but the description below applies mutatis mutandis if negative charges are created on the tire and positive charges on the surface as each wheel 20 rotates positive charge on respective circumference 44 of each tire is transferred to upper end 32 of respective conductor 34 and to edges or points 52 in preferred embodiments where the latter are present since these are regions for preferential charge transfer the positive charge conducts to lower end 36 which is a region for preferential charge transfer and positive charge is transferred therefrom to surface 28 it will be appreciated that the transfer of positive charge from lower end 36 is facilitated both by end 36 comprising sharp points or edges as described above and also by the fact that negative charges are present on surface 28 the negative charges acting to attract the positive charge present on the lower end the transfer is also facilitated by lower end 36 being relatively close to wheel 20 so that the negative charges are relatively undissipated the attraction by the negative charges on surface 28 is particularly applicable in low humidity conditions and or low surface conductivity conditions since the surface charges dissipate relatively slowly under these conditions furthermore as vehicle 26 travels faster the time between separation of charges at region 42 and arrival of lower end 36 over the.