Lombard I've never tried it, but I'd be interested to see if it isn't true also when riding with grossly overinflated 30psi tires, if riding on glassy smooth pavement. Unfortunately, I don't think the Gorilla Tape I use for rim tape would hold up to such an experiment.
I suspect, as long as the tires are rolling round enough, 30psi would actually roll pretty fast until you hit a pebble or a cigarette butt and got bucked off the bike.