Vittoria is proud to be an active and voting member of the ETRTO (European Tyre and Rim Technical Organisation).
ETRTO plays a critical role in standardizing and harmonizing tyre, rim and valve specifications across Europe. Its work ensures compatibility and safety for tyres and rims across all types of vehicles, including bicycles.
Working closely with ISO (International Organization for Standardization), ETRTO develops global standards that are referenced by international bodies such as the UCI (Union Cycliste Internationale). The UCI relies on these standards to ensure the safety and conformity of bicycles and their components, tyres and wheels, used in official races.
For Vittoria, adhering to ETRTO specifications in the design and testing of tyre systems is a commitment to putting safety first. As an active participant in ETRTO technical groups, we contribute our expertise alongside other industry leaders to continuously improve performance, safety, and innovation in bicycle tyres.
Standardization also brings important benefits to end users. One of the most significant is clear, unambiguous tyre sizing.
In the past, tyre dimensions were often based on nominal values that varied between countries and manufacturers—sometimes expressed in inches, other times in millimeters, often inconsistently (e.g. 700c referred nominally to a 700 mm diameter, regardless of actual size).
Thanks to ETRTO, dimensions are now standardized and precisely defined.
By being part of ETRTO, Vittoria not only ensures compliance with industry standards but also actively helps shaping the future of cycling safety and performance through technical collaboration.
Recommended Tyre–Rim Compatibility
The chart above illustrates tyre–rim compatibility as recommended by the European Tyre and Rim Technical Organisation (ETRTO), currently enforced as an ISO standard. It also indicates which combinations are considered suitable or recommended to ensure proper fitting and optimal performance. Additionally, the chart shows the design rim width for each tyre size — the rim width on which the tyre's stated section width is based.
Nomenclature
Stated Tyre Section Width: the overall tyre width as printed on the sidewall, following the ETRTO size designation format: XX-YYY (e.g., 28-622), where:
XX = nominal tyre width in mm
YYY = nominal rim diameter at the bead seat in mm
Stated Internal Rim Width: the internal width of the rim, specified in the ETRTO format ZZ-YYY (e.g., 21-622), where:
ZZ = nominal internal rim width in mm
YYY = nominal rim diameter at the bead seat in mm
Design Rim Width: the internal rim width used as the reference for the tyre's stated section width.
Important Note
When fitting a tyre to a rim with a width different from its design rim width, the actual tyre section width will vary. As a general rule, the tyre width changes by ±0.4 mm for every 1 mm difference from the design rim width.
For example, a 28-622 tyre designed for a 19 mm rim and mounted on a 23 mm rim will have an approximate width of: 28 + 0.4 × (23 − 19) = 29.6 mm, plus or minus the tolerance specified by ETRTO for that tyre size (±2 mm in this case).
Vittoria Advice
We encourage all riders to verify the ETRTO designations on both their tyres and rims and ensure their combination complies with the recommended tyre–rim compatibility chart provided above.
