Pneumatic tire having radially varying tread composition

Abstract

Abstract A radial pneumatic tire for heavy-duty vehicles com- porising a tread portion including a radially outer tread rubber layer and a radially inner tread rubber layer, wherein he radially outer tread rubber layer (7) is an outer tread rubber compound which is composed of, based upon 100 parts by weight rubber, 25 to 75 percent polyisoprene rubber and 75 to 25 percent polystyrene/butadiene rubber, e radially inner tread rubber layer (8) is an inner tread rubber compound which is composed of, based upon 100 parts by weight rubber, 100 to 75 percent polylsoprene rubber and 0 to 25 percent polystyrene/butadiene rubber, the radially in- ber tread rubber layer (8) has a resilient coefficient of from 50 to 70 at a normal temperature of 15 °C and a rupture energy of not less than 400 kg/cm 2 at a temperature of 100 °C. A boundary (10) between the radially outer tread rubber layer (9) and the radially inner tread rubber layer (8) is disposed radially inwardly of a plane (P) which is located at a position of about 1/2 of a groove depth (d 12 ) of each of the circumferential main grooves (12) and radially outwardly of a bottom portion of each of the circumferential main grooves (12). Wear resistances of the radially outer and inner tread rubber layers (7, 8) are substantially equal to each other within ± 10 percent tolerance.

Inventors

• 👤 Eiji Mineki
• 👤 Hideki Matsuda
• 👤 Hidenori Takahashi

Bibliographic Details