Ever since I got the rims mounted on my Vigor, around 70mph-80mph it will shake like a bastard sometimes. It comes and goes, but is there more often than not. Sometimes it will go away at higher speeds, other times it will get worse.

I performed a 4-wheel alignment and had the wheels rebalanced and it still happens.

I've heard two suggestions: Wheel spacers and center rings.

Can someone enlighten me as to what the problem might be and how to fix it?