I'll second the vote for Meguiar's Tire Gel - longest lasting stuff I've found (though doesn't last weeks like they claim). It doesn't brown your tires, smells like grape soda (never understood that one
), and is very easy to put on if your tires don't have alot of writing/ribbing on the sidewalls (which just takes a little more effort to get an even application).
They also make it in a low and high-gloss version. I've never liked the shiny wet look, so I go with the low-gloss version.
Good stuff.
Regards,
- Ryan