The outside edge is worn from a lack of camber, not rubbing. Since there is almost non negitive camber the tire is being rolled on to the outside edge of te tread and top of the side wall.actually that does look like its from rubbing, he doesnt have any camber.
Good call. According to the Spec Miata rules the required rim diameter is fifteen (15) inches. Maximum rim width is seven (7) inches. Minimum weight of wheel shall be 13 lbs without spacers. As SM cars are barely dual purpose capable I give this guy a big thumbs up for being a hard core enthusiast.Probably his daily driver wheels/tires also.