The only thing I would be concerned about is the manufacturing quality of the rim. Having used aftermarket rims in the past and further, being in the automotive profession, I can tell you that there is alot more here than meets the eye. Firstly, the rims manufactured by Ronal for BMW must meet a certan "quality" criteria. I'm guessing most likely the tires are mounted to the rims at the Spartanburg facility and there is a limit to how many wheel weights can be or should be added. As well, usually "we" match the high spot in the rim (indicated by the manufacturer of the rim) to the low spot on the tire (again indicated by a dot or sticker on - ever wonder what all those dots and stickers are on your rims/tires - well now you know). Secondly, what do you think happens to all the rejected rims...they end up with resellers who make no warranty implications. I've seen aftermarket rims that just can't be balanced correctly - you get them close but at certain speeds, they do vibrate and further..this over time will do a number on you and your suspension. So, buying an aftermarket rim does have drawbacks, like how the wheel is balanced (when it was cast or forged) - which brings up another point - forged rims are probably the better ones to go for, lighter and stronger if you can find them - although more $$$. Now, if all you want is the look - crap, go for the aftermarket ones...quality in finishing maybe less but it comes down to what you can afford.