Tread for heavy-goods vehicle tire

A tread for a heavy vehicle tire,

• said tread having a total axial width W and a wearable thickness PMU of material,
• said tread being provided with at least four grooves of circumferential overall orientation on each side of a midplane that divides said tread axially into two parts of equal width,
• said grooves of circumferential overall orientation dividing said tread into a middle region, intermediate regions axially on each side of said middle region and edge regions axially delimiting said tread,
• said middle region being defined as a region of said tread situated between the two circumferential grooves that are axially most closely spaced on each side of said midplane,
• said middle region having an axial width Lm at least equal to 30% and at most equal to 60% of said total width W of said tread,
• a total volume void ratio of said tread when new is less than 17%, said void ratio being calculated as a ratio between a total void volume and a total volume of tread including all voids and evaluated between a tread surface when new and an internal surface extending in said tread parallel to said tread surface when new,
• said internal surface being in contact radially on the inside with those points of the deepest circumferential grooves that are furthest towards the inside of said tread,
• said middle region having a volume void ratio when new that is less than half said total volume void ratio of said tread when new, said middle region comprising a plurality of transverse or oblique sipes opening into said circumferential grooves,
• said sipes having a depth at least equal to 75% of the depths of said circumferential grooves, and
• the number of transverse or oblique sipes in said middle region over one complete turn of said tire being greater than the number of transverse or oblique sipes in each of said intermediate and edge regions.