We found them! This is the original design 19x7.00-8 knobby tire for the Baja Mini Bikes MB165 & MB200 (Tread Pattern P315) that Baja used on their very popular mini bikes models. The aggressive knobs that encircle this rubber beauty are just what you want to sling the mud around with, and unlike V-tread designs, it doesn't matter which direction you have them facing.
The 19x7.00-8 tubeless tire used on a number of small engine size ATVs, go-karts, and specialty mini bikes from Coolster, Roketa, and other fine brands.