I called TireRack technical support and explained the situation. I was told the rubbing probably happened while I was mounting the wheel. This was the first wheel I installed, so I put the wheel bolts in most of the way, and then spun the wheel to see if there was any resistance. Now that I think about it, I did actually feel resistance, but it magically went away after half a spin so I disregarded it. Turns out the wheel was probably angled and the tire was resting against the strut since I hadn't tightened the bolts all the way. This caused the dust to rub off onto the tire for only a portion of the turn. I was also told that if it were rubbing while driving the paint on the strut would likely be rubbed off by now, but in my case only the dirt rubbed off, and the paint appears undamaged. So they think it's not rubbing while driving.
I decided to remount the wheel to see how much clearance there is after torquing the wheel bolts. There's tons of space! Looks like at least 3/4 of an inch or more.
It looks like TireRack was right on, and it doesn't rub while driving!