There are a lot of requests and questions regarding where to purchase contact wheels. As you know there are two types of contact wheels, smooth and serrated. They come in various diameters from 2″ to 14″ with 2″ widths. The most common sizes used are between 6 and 12 inches in diameter.
There are various suppliers in North American, with almost all of the suppliers in the USA.
China has a few contact wheel suppliers that sell on Aliexpress and eBay.
UPDATE September 2019
I have purchased a couple of 10″ wheels from the L-Paladin store to test them and I have been very disappointed with the quality. One wheel had the death wobble and the second wheel had dents to the side of the Aluminum core during manufacturing. I am also not a fan of the circular retaining clips they use versus machined bearing pockets. The major issue with contact wheels from China is the major lack of quality control.
I did contract with a different Southeast Asia manufacture and had them make two different sized contact wheels with bearing pockets machined to my specifications. The quality was excellent and they run true and are very smooth to grind on. The shipping costs from Southeast Asia makes these suppliers more expensive than purchasing from a USA retailer.
I will continue to research and test contact wheels and hopefully add a quality product to the Nexus Grinder product line.