Yep, there were a lot of different versions of the Graupner model airplane tires - I believe the ones sold by Veco are original Graupners from Germany, not sure about others. In any case, where there is still a skin, and tires have not been trimmed, and the high crown removed, that's a sign its the original airplane tires.
Until the urethanes came along, and people found silicones, we mostly used various German sponge tires in our vintage classes. If still at all fresh they worked pretty well, even on a modern polyurethane painted track without glue, but we often had to clean them off with lighter fluid every 10 laps or so... All the Mila Miglia tires use this type of compound, and they often remain fresh - they seemed to be the best of the bunch, along with Rannallis.
At the time, they were always run with traction tonics of course: anything from castor oil to STP!
The disadvantage is that they'll dry out much faster than the urethanes, which don't seem to dry out at all, from what I've seen.
You're right to get into the old sidewinder motors - they're well made and will run forever - I'm on about my third set of brushes for the first one I built up some 20 years ago! If you get new ones, however, be forewarned: they take a long time to run in and get up to speed, at least 2 hours! Worth rezapping them too, if you can find a zapper - but I haven't and mine still run okay.
Rick (DC65X) has done a lot of nice threads on hopping up these motors.