I'm not quite sure what you're asking here. If you prevent values over 99 inches, why is 13.5 inches a special case worth mentioning? Is that you really mean than only values between 0 and 99.9 or so are allowed?
If so, a converter isn't what you need. You need a RangeValidator. Basic JSF stuff.
Customer surveys are for companies who didn't pay proper attention to begin with.