Hi just curious why most people are complaining his tire goes flat on 200 pounds if it’s solid rubber how does a solid rubber tires go flat?

Great timing for this question. I have been moving rocks lately in my wagon, got tired and left them for a few days. I just put the new tires on and now they were flat. Not flat from losing air, literally flat on the bottom from the weight. I unloaded the wagon sure I would need to replace them again with a lesson learned. Do not leave heavy amounts of weight in the wagon for 5 days but two days later, weightless, the tires are round again and I’m good to go. I do live in a rather warm climate so maybe the heat helped them to reshape. I am happy with the purchase.

Are they super-hard like some flat free tires, or do they have some give like a pneumatic tire?

They are fairly hard/dense. Probably equivalent to about 40 PSI in a pneumatic tire of the same size, which would result in a 30%-35% over-inflation.

Will these wheels replace Wheel No. 3339 on Milwaukee hand truck model no. 30080 without any major hassle or modification of bearings, etc.?

Let me say first I know nothing about model number of any product. I bought the wheel based on size of the wheel on my hand truck dolly’s. When I installed them my old wheels were tube type and I had a washer on both sides of the rim. On these I had to remove one of the washers so it would fit. Now with all that said, I really like them. I guess if they don’t fit you could send them back for a refund. I know I haven’t given you a lot of information but I hope you can use some of it.

What is the height from the ground to the center of the hub?

Using the sellers supplied drawings, it shows that the overall height of a tire is 10 inches, therefore the center of the hub (i.e. axles) to the ground would be 5 inches.