I have a friend who had a set of those on his car when we drove to the last National Rally. If he hit even a mild bump in the road, he had a flat. The explanation by the supplier was that they don't fit the rim properly, leaving a pinch gap under the bead (21 inch wheels). Hit a bump and the tube was pinched and that is exactly where he found the holes.
That said, there are others who have not had that problem by inflating the tyres to well above the recommended maximum. Hmmmm.