[Travis Covington]

I assume these are designed to be used as caster wheels on the front of wheelchairs, and as such, I imagine would easily last 8+ years with no issues used in that application. However, when you use them for a different purpose (powered wheels driving a robot) the dynamics change drastically and I cannot foresee them having the same life span. That is not to say that it won't work, but my limited experience with some of the higher strength-to-weight ratio materials leads me to believe that any wheel* that weighs .05lbs does not have the strength to make me comfortable enough to use them on a competition robot.

See if you can find out what the material really is, and that alone will tell you if they are truly stronger than aluminum (and exactly what sorts of loads they can handle). There is no sense taking someones word for it when there is enough information out there to double check for yourself.

Let us know what you find out. I am not aware of any plastic material that is less dense than any 6000 or 7000 series aluminum while also being stronger (or with remotely similar strength even).

It couldn't hurt to re-weigh it too and put something else on the scale of known weight to get a basis for comparison. When looking at the second picture, it definitely looks heavier than .05lbs.