Grandparents bought a set of these for our 8 year old last Christmas. (He weighed about 50lbs at the time). These seem to be a very durable product and they stayed on his feet, but he sank like a stone in light snow. He did only slightly better in packed snow. He wore them 3 times in different conditions and finally gave up. We concluded that we really needed a higher rating (weight wise) for him and since then I've had that confirmed with various sporting goods stores. I would recommend them but not for a child over 45 lbs (and you should consider how heavy they will be when bundled up. As for boot size, I don't think that is as much of a concern, as the strapping leaves ample room for adjustment. I would buy Tubbs again, but would leave a larger weight margin.