I believe mine are the 48" bars, which is the smallest Yakima offers. There is very little overhang. You can cut down any overhang that you don't care for. The rear hangs over a little more than the front because the rails are not parallel (they taper slightly toward the rear).
But, if I were doing it again, I'd get the longest bars they offer and then cut them down because the longest Yak bars (78") are MSRP $50, and my 48" bars were MSRP $50 (I actually got them for $40). If I did it over again, I'd get the 78"ers, chop 'em down with a hacksaw, buy an extra set of end caps, and have a set of 30" bars for free.
