I've never owned a tractor before, but am thinking of buying a used JD 460 tractor with a 400 series front-end loader and pallet forks to move large square hay bales for my horses. Are there any safety issues I should be aware of? Thanks
First off, welcome!
I'm not aware of any Deere tractor called a 460. They had a 460 loader, is that maybe what you saw?
When moving keep the load as low as possible, avoid moving sideways across a hill, and make sure you have enough counterweight on the back of the tractor.
You can lift a max load to full height safely if you move slowly, and have a solid, level surface under the tires, but you can still run into problems. For example, if you didn't see an obstacle and it pinched a tire causing it to go flat suddenly...that would be a nearly instant roll over.
It's unlikely that a single large square bale is a max load for the machine you're looking at, but we'd need more info to be sure. For example, if the machine weighs 5,000lbs, and the loader can lift 2,000lbs to max height, you shouldn't have any issues with something like a large square bale, or even medium round bales.