It really depends on your personal riding style.
Street: Usually a thicker tire to hold up to grinds, hops, hard landings to flat, stuff like that. I'd say 2.20 to 2.40
Park: Thinner and lighter tires usually do the trick. I'd say 1.85 to 2.10 (Don't get me wrong, some park riders run fats)
Dirt: Knobby and fat tires to grip loose stuff. I'd say 2.125 - 2.25
I know KHE makes the MAC series tires that are crazy light. Specialized also makes some fairly light ones, I'm running them now. Maybe Maxxis or Tioga as well. Hope this helps! :D
Scooter kid trying to ride a bike.
@scootereyn