What crosstrack should I have during a holding pattern? I want to know if the ATC is expecting a maximum crosstrack depending of the plane's speed.

I've learn to be at 2.2nm for my holding (with 175kias) but is it just a distance to help me or a rules ?  

I think that my protecting side is higher if my speed is higher too but can I use the whole protexting side  ? 

Thx
If you follow the holding guidelines you will never leave the protected area. This includes performing an appropriate entry, applying correct wind correction, and flying the correct leg length.

ATC expects you to slow to holding speed no later than 3 mins before arriving at the holding fix for planning purposes, and generally doesn't expect you to use the entire protected area. However, the entire area is protected, so you could use it if you wish.