| CPC B60C 11/0323 (2013.01) [B60C 11/0302 (2013.01); B60C 11/032 (2013.01); B60C 11/04 (2013.01); B60C 11/1218 (2013.01); B60C 11/1281 (2013.01); B60C 2011/0346 (2013.01); B60C 2011/1361 (2013.01); B60C 2200/06 (2013.01)] | 18 Claims | 

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               1. A heavy truck tire tread having a longitudinal direction, a lateral direction and a thickness direction, said tread having a ground-engaging contact surface and having a main longitudinal center groove, two main longitudinal shoulder grooves and two main longitudinal intermediate grooves, said five main longitudinal grooves defining six main longitudinal ribs, said five main longitudinal grooves comprising one hidden groove, two open grooves and two partially hidden grooves; 
            wherein each of said two partially hidden grooves comprises openings to the ground-engaging contact surface and undersurface channels connecting adjacent openings, longitudinal sipes extending substantially along the longitudinal direction and connecting successive openings to the respective channel, wherein portions of the longitudinal sipes terminate at a terminal bottom end of the partially hidden grooves in the thickness direction and are located along the partially hidden grooves so as to be below the openings such that the openings are located between the ground-engaging contact surface and the longitudinal sipes in the thickness direction; and 
                wherein said hidden groove comprises an undersurface duct, a hidden groove longitudinal sipe extending substantially along the longitudinal direction and connecting said undersurface duct to the ground-engaging contact surface, said hidden groove being the main longitudinal center groove of the tread, wherein the hidden groove longitudinal sipe extends to and is located at the ground-engaging contact surface. 
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