140 just fine
i use the 140 S12, and have no problems. '99 220 FMF Grarly Rev & TC2 silencer, jetted a little lean.
can certainly understand that you need a little spin once in awhile..., but when it's that slick..., the 140 still spins. when the S12 is no longer "sharp", it loses traction & leaves you wishing for a new sharp 140. can only turn 'em around, once.
i've seen 140 M5B's used on similar set up 220's. perhaps better drive than the S12, but not nearly the side-hill grip. and again..., if it's that slick, it still spins.
come late spring, the 140/soft-terrain tire makes way for a narrower intermediate tire.
bottom line..., depends on where/how you ride.