It will help on any surface, including ice. On dirt or snow, the harder the surface the more the siping helps. Obviously, there is a limit regardless. But if you look into all the hightech snow/ice tires these days the two constants are soft compounds and siping. I've run screws (essentially studs)in the tires of my quad for ice, but the number required to gain significant traction is not practical for paved surfaces. I've also used chains on both the Jeep and the quad and they help but are obviuosly also not suitable for any high speed operation on roads. If you have access to the iron, try it.
