I didn't keep the link but if you search the internet you can find some articles on how to make your own wheel weights. I seen a couple on how to use weights (from a weight lifting set) to make wheel weights also one on how to make them from concrete.
I have a cf struck. them plastic ones seem like they would work pretty good. i don't really want to rig up weight lifting weights on my wheels that would look kinda halfast but a good idea to get you by i guess.
Completely off this topic, where are you located in PA? If you are close enough to me, I would love a chance to see this tractor in person and take a few pictures. I never knew Struck made a wheeled tractor. You're right, the Power King weights will probably fit but finding the 16" weights will be a challenge. Mission had some new ones but they are probably sold out by now.
i live about 30 miles east of pittsburgh if that is close enough you are more than welcome to come check it out. and yes i was thinking of filling the tires. my buddy said windshield washer fluid is a good filler.