Are you looking for a particular brand of wheel or type of wheel? Grinding wheels come in all sorts for grits and hardness. Some are suitable for carbide; others for steel or other materials.
What material will you be grinding and for what purpose? By purpose, think of sharpening carbide cutters or HSS or M2 steel versus removing flashing from aluminum castings, and everything in between. Will the wheel be used for grinding profiles? Do you need a cup wheel or a point? Will it have water coolant, and so forth.
A machinery supply place will have many pages devoted to grinding wheels, because there are a lot of things to consider. Just for pedestal grinders (off hand grinding), a typical supplier (MSC) has over 200 pages of offerings. Norton is a good brand and 3M makes good abrasives as well. There are, of course, other brands, and a lot of house brands that are imported, but are still decent quality.
There are also some simple checks you can perform, if you are buying a simple wheel for a pedestal grinder. One is to support the wheel on a pencil and tap it. It should ring. If not, it may have a hidden crack.
John
