Is that something you're assuming, or something on which you've actually seen statistics? The closest thing I've seen to a fact supporting your statement is an association between poverty and being a victim of sexual violence. They include having to resort to prostitution in their definition of "being subjected to sexual violence", which makes sense... desperate people and their measures and all.
On the other hand, I haven't seen anything, anywhere, that uses actual facts to suggest that impoverished people are more likely to perpetrate a rape. In fact, college campuses have rape rates that are generally greater than the rate for the general population, so I'm not too convinced that poverty is that strong a player. As for conviction, it's a widely accepted truism that the rich are more likely to be acquitted than the impoverished purely because of lawyer power, but I'm not sure anyone will ever know much simply being rich has to do with the conviction statistics. It's not an easily tested value. It sounds good, though, and it's logical, so I'm not going to challenge that directly. I'll just say that I don't think the disparity can be attributed, entirely to poverty, especially since saying that the racial statistics are skewed sort of implies that all black people are poor, which is also untrue.
So, is the statement that poverty is associated with being a perpetrator of rape something that you know is true, or something you believe to be true? If it's the former, I wouldn't mind seeing something that supports it. If it's the latter, how sure are you?