Monty has a bike designed for kids with an 18’’ front wheel and a 16’’ rear wheel. The rear wheel looks beefy and is likely double walled. The tire that fits on it is a 2.4.
It is a fully functional trials bike, but it’s designed for kids. It’s probably very strong, but the geometry would be crappy for a full grown adult. The wheelbase is probably like 800mm (my bike has a 1033mm WB) and the stem and bars are bad. It would be very cramped for a full grown adult.