30 to 70 for the intermediate and 5 to 20 for the high molecular weight glycols still more preferred molar percents for the low intermediate and high molecular weight glycols are from 30 to 45 for the low 50 to 60 for the intermediate and 5 to 15 for the high molecular weight glycols the prepolymer for use in a tire or other article is formed by reacting the low intermediate and high molecular weight glycols set forth above with a multifunctional isocyanate the more preferred are the toluene diisocyanates tdi the two most preferred materials are the 80 20 and 65 35 blend of the 2 4 and 2 6 toluene diisocyanate isomers the ratio of tdi to polyol is commonly expressed in the art as isocyanate to polyol ratio or simply nco oh ratio the isocyanate to polyol ratio may be in the range of 1 9 1 0 to 2 8 1 0 a more preferred ratio is 2 0 1 0 to 2 6 1 0 the most preferred ratio is from 2 1 1 0 to 2 5 1 0 the percentage of free nco in the resulting prepolymer is also in common use for characterizing prepolymers polyfunctional isocyanates used in this invention are not particularly limited but are preferably aromatic and aliphatic diisocyanates and triisocyanates aromatic diisocyanates are for example and their derivatives substituted with alkyl alkoxy halogen or nitro groups e g 3 3 39 dimethylphenyl 4 4 39 diisocyanate or 3 3 39.