What is the proper brand cut off blade to be used on a Ryobi angle grinder?

a very good brand of cut off disks is called "walter" just google walter zip wheels, or cut off disks. as for them not fitting. make you shure that you have the arbors (AKA back up nuts) on correctly there are four possible configurations you ould be putting them on in and only one is correct. try all 4 see which one works. also make sure that anything you put on your grinder is rated for the RPM's dont go overspinning a disk it will explode