So I was in such a hurry to finish painting my stockies that I used a can of paint that
I wasn't supposed to be using on them.

It's some sort of weird enamel.

I noticed it when I came back outside after a few hours to check up on the drying
process of my rims. The other 3 are fine, but this "enameled" one is cracking
and it's soft to the touch.

I tried grabbing sand paper and removing it but it's doing me no good. It feels like
it's rubber and all it does is pretty much smear.

How can I remove this stuff?

Will paint thinner destroy my wheels?

If anyone could help, it'd be great.

 

paint thinner should be fine on them. It deffinetly wont crack the wheels. and it it eats away a tad at the original coating of the wheel, its going to be repainted and impossible to return to stock anyhow. You should be ok. Dont get it on the tires for extended periods tho.