In theory, a thief could do that, but in practice, it's not common. In fact, I haven't heard of it happening, though I'm sure it has happened. They would have to bring a saw and cut through the rim and tire. It would be easy enough, but it seems that thieves don't carry saws. Strange but true. The point is don't measure likelihood of theft by how long it takes. You have to know what tools the thieves carry. They have bolt cutters and cable cutters, but they don't have saws.