Tread for a tire

A tire having an axis of rotation and comprising a crown extended by two sidewalls and two beads, a carcass reinforcement anchored in the two beads, a crown reinforcement radially outside the carcass reinforcement, and a rubber tread radially outside the crown reinforcement, the rubber tread comprising a first radially inner layer C1, and a second radially outer layer C2, and a circumferential groove including a wear indicator, the second layer C2 being configured to be in contact with a ground on which it is running, in new or worn condition, and the first layer C1 having a radially outermost height greater than that of the wear indicator and being configured to be in contact with the ground on which it is running, in worn condition until a radially outer surface against the ground on which it is running is at a level of the wear indicator,

• wherein the tread comprises ribs separated by the circumferential groove with a bottom, a limit of use of the tire being defined by a minimum radial height h of the ribs relative to the bottom of the circumferential groove, VC1 and VC2 being volumes of materials C1 and C2 located in the tread at a radial height greater than a minimum radial height h, and a VC1/VC2 ratio being greater than 15%,
• wherein the rubber composition of the first layer C1 comprises more than 50 phr of a copolymer of ethylene and of a 1,3-diene, a reinforcing filler and a plasticizing system, the 1,3-diene being 1,3-butadiene or isoprene and ethylene units in the copolymer representing more than 50 mol % of all the monomer units of the copolymer, and
• wherein the copolymer of ethylene and of a 1,3-diene bears at the chain end a functional group F1 which is a silanol or alkoxysilane function.