wheels currently produced are made from two different alloys, aluminium
or magnesium, and must have a maximum diametre of 5”. The width of the
wheels may be checked at any point of the competition: the template must
pass liberally until the interior of its top side rests on the tyre.
The template can be introduced in at least three different points of the
wheel circumference in order to prevent deformed readings based on
Wheels made of magnesium are about 35% lighter than those made of
aluminium, they also bend less lengthwise and so the surface of the tyre
functions better, in optimal conditions, with a lower internal air
temperature. Magnesium is a very fragile material and even a small bump
could break the rims. Aluminium rims are more elastic and thus are
more suited to conditions of high grip.
The fixing of the wheels is most important and it should involve a
safety system using nuts with split pin or auto blockage.