wheel size before changing struts

[skaife01]

im looking at getting new rims for my vt and i have been told by a friend that if i get wheel that are more then 2 sizes biiger then standard i need to change the struts, i would like to know if this true.
if i go larger then 17in do i have to change the struts as i was looking at 20in wheels?

[Mick1988]

No you just need to run low profile tyres which you should so anyway otherwise larger diameter tyres would throw your speedo and odometer out