Grease composition for tapered roller bearing and tapered roller bearing

A tapered roller bearing comprising:

• an inner ring member having a tapered raceway surface on an outer peripheral surface that is fitted onto an outer peripheral surface of a hub wheel that has a wheel mount flange formed integrally and rotates together with the wheel;
• an outer ring having a tapered raceway surface on an inner peripheral surface;
• a plurality of tapered rollers that roll between the raceway surface of the inner ring and the raceway surface of the outer ring;
• and
• a grease composition filled around the tapered rollers,
• wherein the inner ring member has a flange part configured to get into sliding contact with the tapered rollers,
• wherein the tapered roller bearing is configured to be used under a high load condition, where the condition of the high load is a maximum contact surface pressure on the inner ring and the outer ring of 0.5 GPa or more and a surface pressure on the flange part of 0.1 GPa or more and,
• wherein the tapered roller bearing is configured to be used as a tapered hub unit that rotatably supports a wheel of a vehicle,
• the grease composition comprising a base oil, a thickener and an additive,
• wherein a frequency in which a storage modulus, which varies depending on a frequency, of the grease composition which becomes minimum is equal to 7 Hz or more,
• wherein the thickener is an aliphatic diurea compound and an alicyclic diurea compound,
• wherein the additive contains an extreme pressure agent including phosphorus in a molecular structure, and
• wherein the extreme pressure agent contains 0.05-0.3 mass % of phosphorus relative to the total weight of the grease composition.