Anyone know the exact diameter of the side tubes on the roof rack? I don't have an Xterra, but am making an antenna mount for one for a 48" 2400Mhz omni. I plan to use a couple u-bolts to attach the bracket to one of the side rails, and I don't know the sixe u-bolt to buy. I don't have an Xterra to test on, otherwise I'd just go measure it (duh).