The tread comprises a plurality of blocks, each block being delimited by transverse or oblique grooves and circumferential grooves. Each block is provided with a sipe which has three branches. The branches have common ends. A first branch is oriented in a transverse or oblique direction. A second branch and a third branch each open when new into a transverse groove delimiting the block. The angle formed between the first and second branches is 100 to 125 degrees, and the angle formed between the first and the third branches is 100 to 125 degrees. After wear, each sipe represents between 45% and 70% of the total wearable thickness, such that the lengths of the three branches measured on the new tread surface, L1′, L2′, L3′ respectively, are shorter than the lengths L1, L2, L3 respectively measured on the tread surface when new.