Floor paint i the obvious answer. There are two main sorts. The cheaper has a solvent that evaporates like normal paint. This will work fine. But if you fancy splashing out a few Baht's more get one of the epoxy-based floor paints.
They have two parts you mix together and they set by a chemical reaction. They tend to be more durable. Solvent-based paint may get scraped through by your motorcycle's side-stand pretty quickly.
The most expensive one is tiles, on the positive side it keeps your garage a bit cooler during the day.