A remix/rebuild of http://www.thingiverse.com/thing:26279 I tried his design but modified it a bit, but given the fact that I do not have the source files and work in solidworks I started anew. The mold is designed around the 8 mm hex hole rim from the link.
Also I still only have a single tire design. But if you feel like it, any half round circle out diameter of 69.5 mm and a wall thickness of 3.5 mm and a design protruding will do I guess.
Work in progress, I'm currently printing these parts for a test run and possible a refinement.

So I like designing thread patterns for tires :)
A crosshatch similar to what Danithebest91 made only suitable for my molds and coarser.
Two different chevron designs one V shaped and one with a step between them. Unfortunately for proper printing I needed to add a little tabs to the chevron mold to support part of the print.
Only the trekkerband (which is a a wrong name btw) has been tested thus far.

Print the wielmal deel A and wielmal deel B and two times the trekkerband. Also get the 8 mm hex rim from Danithebest91.
Drill out all holes, make the oogoo. (cheap silicone + starch or with soapy water).
Fill up the rim, add both thread halves. Leave no air or the tire will have a weak spot.
Push a M8 bolt through wielmal A.
Press the wheel into wielmal A and line up with the bolt.
Add wielmal B, compress with a M8 nut.
Wait a couple of hours.
Carefully remove the wheel from the mold.
Have fun.