My GS came with Metzeler Tourances, and I dunno how many miles you'd get out of em from personal experience.
Then I put on Dunlop D607...that was a fucking mistake. Typical Dunlops, cupped to shit and worn the fuck out at 6k. Fuck Dunlop. They make completely shit sportbike tires, I dunno why I thought they'd make decent multisurface tires.
Currently I'm using Pirelli Scorpion ST, and at 5k on em it looks like there's a teensy weensy flatsopt, about what you'd see on a bird at 2k on a Pilot Road. Most guys I've talked to who use the Tourance and Pirellis usually get 11k+ out of a set, and judging by how mine are wearing, I fully expect to get quite a bit more than 11k.
Those Pirellis stick like fucking GLUE too. I've got no chicken strips on either side of the rear, and am still running 42 PSI in the rear with my fat ass and a shitload of luggage.