visco - elastic tyre balancing compositions comprising 1 ) 85 to 97 % by weight of a glycol ether component comprising one or more ethylene / propylene glycol copolymer ethers of the general formula or the general or mixtures thereof r — och 2 — o —] m n } h r 1 — ch 2 — o —] m n } h ) 2 wherein r is hydrogen or an alkyl group of 2 - 8 carbon atoms ; r 1 is an alkylene moiety of 2 - 8 carbon atoms in which the two substituents are not carried on the same carbon atom ; m is the mole percentage of propylene glycol in the ethylene / propylene glycol copolymer moiety or moieties ; and n is the mole percentage of ethylene glycol in the ethylene / propylene glycol copolymer moiety or moieties , wherein the ratio n : m is in the range from 35 : 65 to 80 : 20 ; each glycol copolymer compound having a number average molecular weight in the range of 2000 - 10000 ; and 2 ) 3 to 15 % by weight of a fumed silica gel former ; said balancing compositions being visco - elastic 1500 pa and 5000 pa at 22 ° c ., a loss modulus smaller than the storage modulus up to a cross over frequency of 10 - 40 hz , and a critical yield stress exceeding 2 pa .