I mean it has clearly racist origins, but I've never actually heard it used in a racist manner in real life.
At least where I was, there were basically zero Asians, "ricers" were (typically but not exclusively) Japanese cars that were customized terribly, as someone else mentioned, all show and no go. You could have American ricers too.
The owners, the "rice boys", were pretty much all white guys.
Well, that's not at all what I said. Japanese compact cars were generally pretty cool and affordable in a way most similar small American cars were not, so of course they get customized a ton more that their American equivilents.
The people who actually made their cars perform were the racers, those who did the truly terrible mods were the ricers.
Yes, racist due to stereotyping. But it was more wordplay for insulting the taste of the person in question in comparison to the racers, not their ethnicity or the origin of their car. Bad taste is pretty universal. And as with pretty much anything in language, people can and clearly have used it as a racial insult. I just don't think that was it's origin.
I am really amused it has morphed into a more positive connotation with the *nix crowd, while still meaning essentially the same thing. Language truly is a living thing.