I don't think you can reshape rubber by a thermal process, after it has been cured by the original manufacturing process. If I'm wrong about that, it would be very useful for all of us to know it can be done. If I'm right, you could still re-cut the tread by using a grinder instead of a soldering iron with the indexing fixture we've discussed. However cutting all that detail with an angle grinder, one feature at a time, would be awfully time consuming.
