But I think of them more as funk artists (with some influences from rock).
Funk IS Rock. Without Rock, you never get Funk. (Unfortunately, the same is true for Disco.)
This was part of the point of my overly long post before... you cannot truly separate many of these from the main, hence why you end up with so many sub-genre classifications.
A great example is Curtis Mayfield. The Impressions are most likely classed as R&B and part of the Rock crossover, but if you listen to Curtis on his own, that very same music is undoubtedly Rock and in many instance will fall into the sub-genre of Funk... even performing the same song.
Listen to Isaac Hayes version of
Look Of Love (B.Bacharach) from
...To Be Continued and
Dead Presidents soundtrack. I challenge you to describe his performance of that Ballad and the guitar solo as anything but Rock. Again, you can see some blurring of the lines, but that solo alone is an
exquisite moment in Rock.
George Clinton? Parliament? Funkadelic? This is all Rock, even when there is Funk, R&B, or even Rap characteristics involved.
Now...
Hootie- Darius Rucker? You can't possibly be putting him in the same sentence as Fishbone!?!!
Regardless...
I'll leave the Ike question for others to debate as well. Tina Turner is definitely a rock singer in my book though. And a pop/ballad/etc.
Ike Turner is "possibly" responsible for one of the earliest Rock And Roll Records (see the story of
Rocket "88"). So whether you classify him as R&B or Rock, he absolutely has a place in the Rock pantheon especially considering the fact that R&B and most ncertainly early Rock were intrinsically intertwined. Likewise, you still have to keep in mind that Rock itself is a subset of Popular Music So you can call artists like Tina Turner or Whitney Houston Pop Artists but they too most assuredly fall into the Rock category.