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:

Example : 28*1 5/8 * 1 1/4 * 1 1/8 or 700 C Course or 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 tire section in millimetres.
  • The second number (590) gives the tire diameter in millimetres.

Glossary

  • 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 tires.
  • 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 tire.
  • Wire bead (WB) : Being made of steel wire, they are cheap.
  • Flexible bead (FB) : Invented and perfected by MICHELIN, they are made of aramide (e.g. Kevlar®). They are lighter and allow the tire to be folded.
  • Tubeless : Tyre fitted without inner tube. It needs specific rims. The advantage of the tubeless tire lies in its ease of implementation. As the rim is already fitted with a valve, the tyre just needs to be fitted and maintained.
  • Tubeless Ready (TLR) : Tubeless Ready tyres can be fitted without an inner tube provided that a tubeless wheel is used, the maximum pressure is not exceeded, sealant is added and the tire pressure is checked before each ride.
Fitting Mountain Bike tubeless tire

Watch video

Michelin Montage Pneu VTT Tubeless

fitting a Michelin competition tire
Watch video

Vidéo montage d'un pneu course Michelin