Wheel sizes FGP 2023
In all the events under the World Skate umbrella, all skaters up to 12 years old (under 13) may use wheels with a maximum diameter of 90 millimetres and the skaters up to 14 years old (under 15) may use wheels with a maximum diameter of one hundred (100) millimetres.
https://www.worldskate.org/speed/about/regulations.html?download=5757:wsk-speed-rulebook-2023