Method for characterizing a tire in terms of uniformity

A device for characterizing a tire in terms of uniformity, the crown of the tire containing welded metal parts, the device comprising:

• a frame;
• a rotary support mounted with the ability to rotate relative to the frame and intended to accept the tire that is to be characterized;
• a measuring member for measuring an angular position of the rotary support which is secured to the frame;
• at least two measuring members secured to the frame and positioned respectively in such a way as to measure, for each angular position of the rotary support, an internal-surface geometry and an external-surface geometry of the tire simultaneously as the rotary support rotates;
• and
• an electronic control unit comprising an acquisition module for acquiring internal-surface and external-surface geometry signals pertaining to the surface geometry of the tire coming from the measuring members,
• wherein the electronic control unit-comprises a module for determining thickness variations of the tire for each angular position of the rotary support on the basis of the internal-surface and external-surface geometry signals, and a module for converting the thickness variations into variations in mass as a function of a predetermined mean density of the tire, the conversion module being configured to detect defects in welds of the metal parts of the crown of the tire and apply a predetermined different density to the defects, and
• wherein the conversion module comprises analysis means for linking geometric measurements of a model of the tire or a serial number of the tire, the tire model or serial number being associated with a density map of the tire, the density map being a correlation between density values of semi-finished products that make up the tire and an azimuthal position of each weld on each semi-finished product that makes up the tire.