I use to get a catalog from Goodyear. They make a belt with a chevron style of cogs. They also make and sell pulleys for their belts. the idea is with the chevron groves, you don't need a rim on the pulley to keep it on the pulley. The chevron keeps it running true.
I'll try to find a url to the belts and maybe where you can get a catalog. If we ever again ran K30 UAS type stuff, I was going to try the belts and pulleys.
This might be it. Just did a quick look to maybe get close.