As the subject stated I was curious if there was some sort of rule to be followed or if they should always be used. I figured this would be helpful to me in the future as well as other members.
More specific for my case though, I have an 09 WRX and know the stockers are 17x7 et55 and have a set of RPF1s that are 17x8 et45 and ready to put on. If they happen to be required, does anyone know the size offhand? If not, no biggie.
Thanks for your help!