i asked jagex once about it apparently there's 2 "wheels" for ur drop the first one has a certain place on it that puts u through to the 2nd wheel, and the 2nd wheel is where u could potentially get a rare drop if ur lucky enough to hit the first "magic number" on the first wheel, the ring of wealth only effects the 2nd wheel, giving u a higher chance of getting the rare drop on the 2nd wheel for the most part it has no effect on your drop