Rubber compositions comprising a precipitated silica with the following physico-chemical properties: TABLE-US-00001 BET surface area 35 to 350 m.sup.2/g BET/CTAB surface area ratio 0.8 to 1.1 Pore volume, PV 1.6 to 3.4 ml/g Silanol group density 6 to 20 ml/(5 g) Average aggregate size 250 to 1500 nm CTAB surface area 30 to 350 m.sup.2/g DBP value 150 to 300 ml/100 g V.sub.2/V.sub.1 by Hg porosimetry 0.19 to 0.46 DBP/CTAB 1.2 to 3.5.