Hi guys.
I had a similar experience with my ranger back in late 2008. There were no clunks or warnings for me though. I was cruising down the road at night, and there was a bump about like hitting a small bump in the road. My peripheral vision registered movement on the passenger side, and I looked over to see an orange glow outside the vehicle. I could not track the wheel in the dark, and my first thought was that it sheared the lugs somehow. The ranger handled very easily, I let it slow to about 15 before attempting to pull off the road, though it did not get far off the road before sticking.
Upon inspection it turned out that the rotor disappeared with the wheel, all that was left was a bare spindle. The tire was close to a hundred yards behind me, stuck in the snow bank. The rotor was still attached to the rim, caliper and all. Apparently what happened was the wheel bearing had overheated and failed, I had just replaced it about a week or two earlier. As the wheel flew off the spindle, it tore the threads apart, wrecked the locking hub, and yanked the brake lines out. Thankfully the parts store comped me on many of the parts, since they felt that they sold me a faulty bearing for the previous work.
Everyone I spoke with about the wheel flying off was surprised that the truck did not flip, as many here have mentioned. I think the asphalt road helped keep it upright, as it could not dig in immediately, as well as staying on the road until I had decelerated from the 55-60 mph I was doing when the wheel flew off. The truck handled beautifully though, I have hit potholes that caused more of a bump than was felt at the moment the wheel flew off.
Wow, this has gotten long quickly. Well, I am glad that everyone is safe, and your truck did not roll either. Thanks all for the information resource, I have found answers to a number of questions about my truck here, and finally had to register to share my tale after reading this thread today.
-Prymal'Dark