Over the course of a lifetime of owning horses, mainly QHs and large pony types, they've always worn an 0 or 00 shoe (if shod). Now I have a three year old 15hh (ahem, full-figured) Haflinger who will be getting her first shoes next month when she goes for training and the farrier tells me she is probably a size three or four. Her feet don't look that big to me but the man knows his job. After the other horses it sounds like she has Sasquatch feet...it got me to wondering if there is an average size, one that accounts for the largest volume of commercial shoes. Curious to hear what other horse owners say about their equine's tootsies.
My current 16.2h TB wears a 3, and had 4s in the past (his platter phase). My first horse, an Appendix QH ~16h wore 2s, I think. Then my dainty TB gelding 15.3h or so wore 0s.
There was a boarder at my barn with a Haffie, and he wore at least a 2 and probably a 3. They are more of a pint sized draft-pony than a pony-pony, if you get what I mean. A TB and a Clydesdale may both be 16.2h, but the Clyde is going to have bigger hooves due to its build.
Failure is always an option*
*As long as you figure out what you f'ed up and fix it! -Me
I don't think there is a real average, except that the current "light horses" seem to run smaller hoofed, with 00 thru size 2. This would cover a lot of animals, various breeds and sizes, but they don't vary a lot in hoof size to manage the weight above.
Haffies, Cobs, other heavier boned animals, not bred to be just "pretty", still tend to have size and substance under their bodies because they do "real work" in the hands of most owners and breeders. Much will depend on the use of the Breed, in having good hooves of size under them, and aid in longer usability of the animals. I wouldn't think having size 2 or 3 in shoes on those kind of animals is any problem.
The problem comes when many owners don't RECOGNIZE a proportional hoof size under an animal, whether he is substantial or not. My older breeding Appy mare of 14.2, 900# fit, was wearing 1's in front, 0's behind. Thick walls, thick soles, carried a good load of rider, saddle, and didn't ever have hoof issues with her proportional hooves. Saddlebred, Gaited horses often have hooves of size, longer toes to manage the weight above, which non-Saddlebred folks want to shorten and make smaller! These kind of horses NEED that size and length to do their work. Hooves are not platter sized, but sure NOT small feet. Horses stay sound in work, last for years if shod and trimmed to leave hooves larger. Just talking about the "common use" horses, Trail, Pleasure, Driving, not the ring long-toe horses of that breeding.
My foundation bred Appy geldings, one 16 hands and the other 16.3, wore size 3 or 4s. My TB Appy cross, 16.2, wore 0s. My current Araloosa wears 3s and 4s. Front only band was barefoot until this drought made the ground so hard.