Tire Markings
ETRTO Standard Marking
The ETRTO marking is a unit of measurement standardized at the European level and recognized worldwide for tire dimensions. It is provided on all tires in addition to the dimensions given in millimetres or inches.
An ETRTO marking may appear as follows on a tire:
Example: 32-590 (650x32A)
What does that mean?
The first number (32) indicates the tire section width in millimetres.
The second number (590) gives the tire's inner diameter in millimetres.
The numbers in brackets (650x32A) correspond to the marking in millimetres, explained below.
Marking in Millimetres
Often used for road or city tires.
A marking in millimetres may appear as follows on a tire:
Example: 650x32A (32-590)
What does that mean?
The first number (650) indicates the overall outer diameter of the tire in millimetres.
The second number (32) indicates the tire section width in millimetres.
The letter A designates a rim with a 590 mm diameter.
The numbers in brackets (32-590) refer to the ETRTO marking explained above.
Marking in Inches
Mainly used for MTB, city, and gravel bikes.
A marking in inches can appear as follows on a tire:
Example: 26x1 3/8 x 1 1/4 (32-590)
What does that mean?
The first number (26) indicates the overall diameter of the tire in inches.
The second number (1 3/8) denotes the tire height, in inches and fractions of inches.
The third number (1 1/4) gives the tire section width, in inches and fractions of inches.
The numbers in brackets (32-590) refer to the ETRTO marking, as explained earlier.
Special case of marking in inches:
Example: 29x2.40
What does that mean?
The first number (29) denotes the overall diameter of the tire in inches.
The second number (2.40) is the overall cross-section, typically used on wider MTB tires.
Technical Terms
Below, in alphabetical order, you will find simple definitions of technical cycling terms.
B >
Bar: A unit of air pressure commonly used for tires. In English-speaking countries, including Canada, PSI (pounds per square inch) is also widely used. Michelin provides tire pressure guides in both Bar and PSI.
C >
CO2 Cartridge: A compact canister used in emergencies to inflate a tire without a pump. It requires a specific adaptor to attach to the valve and release air. Commonly used for road and gravel cycling in Canada where space and weight are concerns.
Compressor: Also called an air compressor, it is often found at petrol stations. While primarily intended for cars, it can be used for bicycles with Schrader valves, provided the compressor has a cycling-friendly setting.
E >
E-25 / E-50 Bikes: E-25 bicycles are electric-assist bikes with motor assistance up to 25 km/h.
E-50 bicycles provide motor assistance up to 50 km/h.
These classifications are important in Canada where e-bike regulations vary by province.
ETRTO: Stands for European Tyre and Rim Technical Organisation. It defines internationally recognized tire and rim sizing standards, ensuring compatibility across brands and regions.
F >
Flexible Bead (FB) or Foldable Bead: Invented and perfected by Michelin, these are made with aramid fibres (e.g., Kevlar®). They are lighter than rigid beads and allow the tire to be folded, which is especially useful for Canadian cyclists who need compact, portable gear.
G >
Gum Wall (GW): A sidewall design coated with a rubber layer to provide extra stiffness and tear protection. The main benefit is enhanced resistance to sidewall cuts, helpful in rougher off-road conditions.
Gum-X: Michelin’s GUM-X Compound is formulated to optimize grip and rolling speed. It is adapted across various product categories in the MICHELIN tire range, depending on the intended use, such as road, gravel, or mountain biking.
M >
Magi-X: MICHELIN MAGI-X Compound is designed to deliver maximum grip without compromise. This compound is adapted to each product category in which it appears within the MICHELIN range.
MTB: A commonly used abbreviation for Mountain Bikes.
O >
Overlap: The central overlapping section of the tire casing.
P >
Presta Valve: A narrower valve than the Schrader, typically used on road and performance bikes. It requires unscrewing the valve core to inflate.
See our article on tire valves for more details.
Protek Max: Michelin’s puncture-resistant inner tube. It combines liquid sealant, a square-shaped profile, and butyl technology for excellent pressure retention.
More information available in our article on MICHELIN Protek Max.
P.S.I. (Pounds per Square Inch): A pressure unit commonly used in English-speaking countries, especially for tires.
Bar is the alternative unit more widely used in Europe. Michelin provides pressure tables using both PSI and Bar units.
R >
Rolling Resistance: The friction created between the tire and the ground. Along with air resistance and gravity (particularly when riding uphill), it is one of the key forces that makes pedalling more difficult.
See our article on rolling resistance for more information.
S >
Sealant: A self-sealing liquid used in tubeless-ready tires or tubular inner tubes. It plugs punctures automatically, allowing you to keep riding without stopping.
See our article: "How to use bike tire sealant".
Section: The width of the inflated tire, measured from sidewall to sidewall.
Shore: A unit of hardness for elastic materials, ranging from 0 (soft) to 100 (hard). Often used to indicate the firmness of rubber compounds in tires.
Schrader Valve (Standard): Known as the standard valve, the Schrader is the same size as a car tire valve. This allows you to check or adjust pressure at a gas station, a common solution in Canada when a pump is unavailable.
See our article on tire valves.
Skin Wall (SW): A type of sidewall that is semi-transparent, allowing the casing texture to be seen. Benefits include lightweight construction, flexibility, and performance.
Suspension Travel: The amount the front and/or rear wheel can move vertically to absorb shocks and handle uneven terrain.
T >
TPI (Threads Per Inch): Indicates the density of threads in the tire casing. A higher TPI means a tire is generally lighter, more supple, and responsive.
Tread: The rubber part of the tire that comes in contact with the ground. Tread design affects grip, rolling resistance, and overall performance.
Tubeless: Tire fitted without an inner tube. It requires specific rims. The advantage of the tubeless tire lies in its ease of implementation. As the rim is already fitted with a valve, the tire just needs to be mounted and maintained.
Tubeless Ready (TLR): Tubeless Ready tires can be fitted without an inner tube, provided that a tubeless-compatible wheel is used, the maximum pressure is not exceeded, sealant is added, and tire pressure is checked before each ride.
Tubetype: A standard type of tire that contains a removable inner tube.
Tubular: A tubular tire is a type of bicycle tire that is sewn around the inner tube to form a torus. The whole assembly is then glued to a tubular rim.
Tire Sizes: On your sidewall, your bike tire size will likely be given in one of these three formats: ETRTO measurements (for example: 23-622), imperial measurements (for example: 29 x 2.10), or metric measurements (for example: 700 x 23C). For more information, see our article "Bike Tire Sizes Explained."
U >
UCI: The International Cycling Union is an organization whose aim is to develop and promote cycling in cooperation with national federations.
UST: Universal System Tubeless is a standard for tubeless tires in which the rim and tire are considered as a single system.
W >
Weight: The weights stated are provided 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.
Wire Bead (WB): Made of steel wire, they are more affordable than flexible bead tires.
