A tread rubber composition improved both in grip performance on ice-covered and snow-covered road surfaces and in abrasion resistance is provided. The tread rubber composition contains aluminum hydroxide having an untamped density of not more than 0.60 g/cm.sup.3, a DOP oil absorption of at least 70 cm.sup.3/100 g and less than 250 cm.sup.3/100 g, and a BET specific surface area of at least 30 m.sup.2/g and not more than 350 m.sup.2/g in an amount of 5 60 parts by weight with respect to 100 parts by weight of a rubber component containing at least 50% by weight of at least one of polyisoprene rubber and polybutadiene rubber. The tread rubber composition has a tan.delta. peak temperature of not more than -45.degree. C. and a type A durometer hardness at 0.degree. C. of not more than 64.