What sort of SAS clamp is it? We have a red one on the University Ribcraft that looks like this:
And on the box it says it is suitable for wheels up to 15" Diameter. It starts at 10".
A point to note on that clamp if you own one is that if not correctly fitted, the bar that is tightened on the inside sometimes bites into the tire, not onto the wheel rim - making the clamp easy to get off by deflating the tire! When the wheelclamp is put on, you have to ensure that there is no gap between the bottom of the bar and the tyre, ie it is at it's maxiumum extension, to ensure a safe fit.