You won't tan if you're using sunscreen that's any good. If you want a tan get it sprayed on. A tan is never ever healthy. A glow, yes. A tan, no. This is coming from Australia here skin cancer is one of our biggest killers. Don't tell people to go get tanned easy in the sun, fuckstick.
There's nothing unhealthy about a tan. Its the UVR itself that's the danger. That being said, obviously an excessive tan means being exposed to excessive UVR.
If you don't figure you'll get a sun burn, then there's no reason to use sun screen.
A tan is you're body defending itself against the radiation from the sun. Your skin produces more melanin to block and protect against future damage. So while technically a "base tan" helps protect you from future exposure, the tan itself is a sign of skin cell damage caused by the sun.
I didn't wear it for half of today thinking, it's only Britain. Then although I wasn't that bad when I put it on but now both my knees, ears and my face are burnt. Fucking British weather.
I wear sunscreen 24/7, even in the winter. I still manage to get a bit of a tan. I know far too many people my age that look 10 or more years older then they are. Plus I'm insanely pale.
If you don't figure you'll get a sun burn, then there's no reason to use sun screen.