That's a really good question. I measured my metal ones, as I don't have the Cathe ones. My 10lb weights are apprx. 9" in diameter. So, that would only leave me 4 1/2" (not even figuring the bar width) to slip under. Vinyl weights are usually a bit bigger in order to be able to fill them with sand. So, I did an Amazon search, and it looks like they end up being just under 11" in diameter. With the grip handles in them that Cathe has, though, I think they'd have to be even a bit bigger than that in order to be able to fit the same amount of sand in one with grip holes as without. So, I'm guessing around 12" in diameter? Plus, your bar would take up some of that space. So, I guess it would depend on the size of your thighs as far as if you'd be able to slip under that small of a space or not. Hopefully someone that already owns Cathe's weight plates will answer and give you the exact diameter of the 10 lb. plates.