Most, but not all tourists say that touring is riding somewhere, staying overnight, and continuing by at the least riding back the next day. So at least a multi-day ride, but often multi-week, or multi-month rides. For those kind of tours 30 mile days are typically about the minimum that folks tend to average and considered short, 50-60 is very common, 70-80 longish, and much longer than that are usually considered long.