I will say you have to relate this 2 stats (VPIP/PFR )
tigh player: 15/10 or less
good player: 25/20 aprox
loose player: 35/25 or more
bad player: 50/20 or more
Assuming that it's VPIP at a 9-handed table, for me I would say approximately:
VPIP <= 16%: Player is tight
VPIP >= 24%: Player is loose
I also agree with Japg that you would usually want PFR to put this figure into context, although that's more a measure of aggression rather than tight/loose.