Let me get this strait, Superman can lift 3000 tons but can't hold up a ferris wheel without bouncing boys help? I know it's a cartoon but cmon. Anyone who can lift 3000 tons should be able to lift 10 ferris wheels with one finger. I've been waiting 20 years for this cartoon. I hope it get's better.
That was certainly a factor. He didn't want people to see Clark Kent holding a ferris wheel over his head. That would tend to draw people's attention to the fact that he was superhuman.
The great Ferris Wheels of Chicago was 1,191 tons in 1893, so it isn't a stretch to beleive that this one could have been in that neighborhood. You also have to figure that this is Superboy, not Superman, and the heights of his strength might not have been realized yet. There is also the fact that it is not only heavy, it is quite unwieldy as well, making it difficult to control no matter if you are able to lift it. Ever tried to lift something heavy that was bigger than you (a wardrobe perhaps)? The difficult part is not lifting the weight, it is controlling the weight once you have it lifted, especially if you then have to move it.