Nice. For those of you who don't know about nice mtb components, you could buy four nice rims and tires for your 4Runner for the cost of these two rims. Sorry for the derailment OP, carry on.
Yes, really neat wheels so long as they are in top working condition, but be wary of proprietary designs like the cobalt and many of the mavic wheels. Not to knock the products, but just consider the PITA you might run into if you need to fix one on the trail/out of town/quickly in town. I work at a bike shop and problems like this occur all the time, and almost nobody has the ability to fix proprietary wheels at a moments notice, especially not at the local trails. Good looking bikes though, you single speed guys are crazy!
You can't go wrong with the Thule T2.
Back on subject, the Thule T2, Yakima hold up, and many of the Kuats like the NV or some others are great. This type of rack (T2 atleast) offers the ability to seamlessly move any type of bike from 20" wheel to 29er, road or MTB, full squishy downhill or SS fully rigid. Also, I cannot stress the importance of protecting the bike by securing it by the wheels and not the frame. Hanging racks can damage paint/cables/etc and lead to premature wear on the hubs if you dont secure the wheels down. As you go down the highway the wheels are left spinning, often very fast and they heat up the hubs. Platform style racks are simply the absolute best way and can accomodate darn near any bike made. As far as height goes, any of the platform racks will be below roof line. I have an XL Enduro 160mm that has plenty of clearance, I can get you pics if needed.
Lots of words, but I strongly vote for a platform style rack if you can afford the $250 or so that they cost. I run a T2, and it has integrated cable locks that stow away in the arm when not in use, and it even came with a locking hitch pin. 2" or 1.25" receiver options. Best value rack out there, protect your bike and keep your sanity as well. They are very easy to operate.
If you have any more questions about bike racks let me know, finally a topic that I can contribute too on the boards.
-Toby