Tire sidewall for a heavy civil engineering vehicle

1. A method for indicating attacks on a tire for a heavy vehicle, the tire comprising a tread, the tread comprising a tread surface having two axial ends extended radially inwards by two tread end faces, each tread end face being extended radially inwards by a sidewall external face, a tread end face and the sidewall external face extending it radially inwards constituting a tire lateral face, the tire lateral face being provided with two adjacent circumferential grooves of different depths, the method comprising:

a first step of applying a retroreflective covering material to said circumferential grooves of the tire lateral face having different depths allowing visual detection in an environment of darkness of that part of tire lateral face having the covered grooves;

a second step of using the tire in a mechanically aggressive environment that exposes said retroreflective covering material to mechanical attack; and

a third step of identifying, in an environment of darkness, attacked zones of the part of the covered grooves initially covered with the retroreflective covering material and now devoid of said retroreflective covering material as a result of the mechanical attack experienced by the tire in said second step, and determining a depth of attack on the tire based on which of the covered grooves remain covered by said retroreflective covering material in said attacked zones.

2. The method for indicating attacks on a tire according to claim 1 , wherein the first step comprises applying the retroreflective covering material to at least part of at least one sidewall external face.

3. The method for indicating attacks on a tire according to claim 1 , wherein the first step comprises applying the retroreflective covering material to at least part of at least one tread end face.

4. The method for indicating attacks on a tire according to claim 1 , wherein the first step comprises applying the retroreflective covering material of coating product type.

5. The method for indicating attacks on a tire according to claim 4 , wherein the first step comprises applying the retroreflective covering material of the coating product type containing glass microbeads.

6. The method for indicating attacks on a tire according to claim 1 , wherein the third step of identifying, in an environment of darkness, the attacked zones of the part of at least one tire lateral face further comprises a step of locating the attacked zones of the tire lateral face.

7. A method for indicating attacks on a tire for a heavy vehicle, the tire comprising a tread, the tread comprising a tread surface having two axial ends extended radially inwards by two tread end faces, each tread end face being extended radially inwards by a sidewall external face, a tread end face and the sidewall external face extending it radially inwards constituting a tire lateral face, the method comprising:

forming first and second adjacent circumferential grooves in the tire lateral face, the first groove having a greater depth than the second groove;

applying a retroreflective covering material in each of the first and second grooves allowing visual detection in an environment of darkness of parts of the tire lateral face having the covered two grooves, the applied retroreflective covering material being of greater depth in the first groove than in the second groove;

using the tire in a mechanically aggressive environment that exposes said retroreflective covering material to mechanical attack; and

identifying, in an environment of darkness, attacked zones of the part of the first and second grooves initially covered with the retroreflective covering material and now devoid of said retroreflective covering material as a result of the mechanical attack experienced by the tire in said using step, and determining a depth of attack on the tire based on which of the two grooves remains covered by said reflective covering material in said attacked zones.