Technical Glossary

Understanding the various markings and other technical information

Marking in millimetres


Example: 650x32A (32-590)

  • The first number (650) denotes the overall diameter of the tyre in millimetres.
  • The second number (32) denotes the tyre section in millimetres.
  • The letter A indicates that the rim is a 590 mm.

Marking in inches

Example 26*1 3/8 * 1 1/4 (32*590)

  • The first number (26) indicates the overall diameter of the tyre in inches.
  • The second number (1 3/8) denotes the tyre height in inches and fractions of inches.
  • The third number (1 1/4) gives the tyre section in inches and fractions of inches.
Special case of marking in inches:

Exemple : 28*1 5/8 * 1 1/4 * 1 1/8 ou 700 C Course ou 32-622

  • The first number (28) denotes the tyre's overall diameter in inches.
  • The second number (1 5/8) gives the height of the tyre in inches and fractions of inches.
  • The third number (1 1/4) indicates the tyre section in inches and fractions of inches.
  • The fourth number (1 1/8) denotes the width of the rim which accommodates this tyre in inches and fractions of inches.

ETRTO standard marking

Example : 32*590 (650*32A)

  • The first number (32) indicates the tyre section in millimetres.
  • The second number (590) gives the tyre diameter in millimetres.
  • ETRTO : European Tire and Rim Technical Organization
    The Gum Wall (GW) sidewall is coated with a layer of rubber to give it stiffness and protect it.
    Advantage: resistance to sidewall tears
  • The Skin Wall (SW) sidewall allows us to make out the texture of the casing through its transparency.
    Advantages: lightweight, flexible and efficient.
  • Overlap : Central part of the casing
  • Weight: The weights stated are given as a guide with a tolerance of plus or minus 7 %.
    This variation is due to the natural elements inherent in the construction of tyres.
  • P.S.I.: Pound Per Square Inch or BAR or Kg/cm²
  • Section : Width of the inflated tyre from sidewall to sidewall
  • Shore is a unit of measurement ranging from 0 to 100. This unit measures the hardness of elastic products. (From 0 soft to 100 hard)
  • TPI : Threads Per Inch- number of threads per inch
    This measurement represents the density of cords in the tyre casing. The greater the density, the lighter, more flexible and mobile the tyre.
  • TR : Rigid bead wire. Being made of steel wire, they are cheap.
  • TS : Flexible bead. Invented and perfected by MICHELIN, they are made of aramide (e.g. Kevlar®). They are lighter and allow the tyre to be folded.
  • Tubeless: Tyre fitted without inner tube. It needs specific rims. The advantage of the tubeless tyre lies in its ease of implementation. As the rim is already fitted with a valve, the tyre just needs to be fitted and maintained.

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