Rubber other various ingredients.

A rubber composition for the tread of a tire comprising a diene polymer is synthesized by emulsion polymerization and having a polar group in its molecule as a rubber component, and 5-80 parts by weight, based in 100 parts by weight of the rubber component, of an inorganic filler represented by the following formula (I): nM or xSiOy or zH2O (I) wherein M is an oxide or hydroxide of aluminum or magnesium, and m is an integer from 1 to 5.