I would have to say a factory aluminum Rincon/Rubicon rim.If you can find a set ot Oem Grizzly 660 rims,they are the lightest that I have seen,I had a 2002 660 and those rims were xtra light and strong,strongest part of the bike actually,only part that didn't break(seriously).They have the same bolt pattern too.The aftermarket ITP C series like I have are light but the offset they give you gets you filthy and puts alot of fatigue on driver with over 27 inch tires!!!!!!Look good though...I was wondering if I ever bought another bike,if you could order ITP alums and ask for the factory backspacing and offset?Anyone ever done this,if you could that would be great?I know the rims they sent me stick out about almost 2 inches,you alway's end up cross rutting other peoples trail due to the wider stance of the tires,rubs tires and fenders more on tight tree trails,put's strain on rider also.Sorry for long chat guy's........