Tread for a tire

An asymmetric tread for a snow tire comprising a rubber composition which comprises:

• at least one diene elastomer,
• a reinforcing inorganic filler, and
• a plasticizing system comprising a liquid plasticizing agent in a content B of between 10 and 60 phr, said liquid plasticizing agent being a vegetable oil,
• wherein the tread comprises:
• a tread surface intended to be in contact with the ground when the tire is running,
• a sequence of basic patterns arranged in a circumferential direction (X), wherein each basic pattern has a width (Wm) that extends in a transverse direction over at least 80% of the width (W) of the tread, each basic pattern has a pitch (P) extending a distance in the circumferential direction, and each basic pattern comprises a plurality of raised elements, one or more of which are provided with sipes opening onto the tread surface, wherein each sipe has a width of less than 1 mm and a depth of at least 3 mm,
• wherein, for each basic pattern, a sipes orientation level (NO) is defined that corresponds to
• ∑
• i
• ⁢
• 
• li
• *
• α
• ⁢
• ⁢
• i
• 
• P
• *
• Wm
• where i is the number of sipes in the pattern, li is the length of the ith sipe on the tread surface, P is the pitch of the basic pattern, Wm is the width of the basic pattern and αi is the positive or negative angle formed on the tread surface by the ith sipe with the transverse direction, where |αi|≤45 degrees, said sipes orientation level being greater than or equal to 1.5 degrees/mm, and
• wherein the tread comprises a median dividing the tread into an inboard portion and an outboard portion, and the plurality of the raised elements on the inboard portion are provided with sipes at a steeper angle relative to the transverse direction than the plurality of the raised elements on the outboard portion, and the sipe orientation level for all the plurality of the raised elements in the inboard portion is greater than 2.