The new Metzeler Karoo 3 front tire is available in the standard size for a 2-1/2" GS rim which is of course a 110/90-R19. But it's also available in a 120/70-R19 designed for the 3" rims used on the new water-cooled GS. Note that in the above pic--which appears to be an "official" photo from Metzeler--that looks like they got a 120/70 on the watercooled GS 3" rim. From the Metzeler website--Innovative belt structure, with a single ply of steel cords wrapped at 0° around a radial carcass. Patented technology by Metzeler for both front and rear high performance tyres. Steel features a higher stiffness than the traditional textile material used and also reduces tyre weight. A steel belted radial reduces the dynamic deformation of the tyre under centrifugal forces giving the tyre excellent high-speed stability. Steel is an excellent conductor, therefore providing a more uniform heat distribution which allows higher mileage and wear characteristics are more uniform.If I can get the 120/70 to hold its bead on my hack, it would give me a little wider footprint and about 4mm more clearance between the tire and the mudguard. But the big question is if it will hold the bead. I'm not worried about it in the dirt--it'll slip before it'll bust the bead. But on pavement when I'm putting lots of lateral force on the tire carcass (lateral force that we know moto tires are not designed to handle) I'm wondering if squeezing it down onto a too narrow rim will cause the bead to break resulting in a sudden :eek1 loss of air pressure. Or am I gonna be OK? Yay or Nay?