I picked one of those up on e-bay for $60, works "okay" as a bead breaker then the usefulness falls apart. Center bolt isn't long enough to mount a rear wheel properly and ended up screwing up a set of rear wheel bearings in the process.
Now this was on a 919 and I can't tell you if it would be any different on an ST, but if you want to try I'll send it to you for the cost of shipping.
When I'm due for tires again I'm going this route from Harbor Freight Tools
The harbor freight one goes on sale all the time for something like 30 bucks and screws on top of the grayed out car changer mounting base with the bead breaker.
The lever that comes with it isn't the best for demounting or mounting but spoons work, the bead breaker on the base works ok. Cut up pc of plastic milk jug works to protect the riim depending on what kind of irons you have.
Also you'll want a pc of round stock that fits thru the wheel bearing.
The rim clamp tabs are just painted metal but you can fabricate some chunks of delrin block that fits in the welded section. The tang adds a little bit of extra support.
Give me a sec I'll snap a picture.
Some sistered up pcs of cutting board would probably work.