---------I noticed some of the new wheels I bought this summer were balanced from the factory (had lead weights stuck to the inside of the rim, but some didnt. I want them to last as long as possible so I wanted to check the ones without weights to see if the balance was okay.
I couldnt find anyone in the area (including large truck shops) that were able to balance the wheels I have. The wheels weigh almost 500 lbs each and the shops that could handle the 46" diameter, couldnt handle the weight. Anyway I decided to build a simple balancer. I bought a takeout hub assembly for $10, and then machined some endplates for it, pressed bearings in and slid a shaft through it. So far I have just used a jack stand on one side and then jacked up the other side so the wheel is off the ground, the heavy portion of the wheel eventually settles at the bottom and I'll just attache the stick on lead weights to the opposite side until things are about even. It works really good (although I havent attached the weights yet). The Hub wasnt even balanced at first so just the hub by itself would spin back and fourth until it finally rested with the heavy portion on the bottom. I'll add some weight to the other side to even that out. I figure it took some time to make, but easily paid for itself with what it would have cost to balance just 1 tire (assuming I could have even found a place to do it).
Only you will know how easily the wheel tends to rotate freely with the axle resting on the Vee Blocks. Some grease might be advisable. The only other thing you could consider is making a pair of rollers which the supporting axle would rest on. The links show how model aircraft balance propellers. This setup should give you a freely turning support axle to work from.
It looks like this
http://www.rundquist.com/images/stuhrpb.jpg
https://www.modelairplanenews.com/wp-content/uploads/2014/02/Capture6.jpg