Stupid 18" back wheel!
No modern radials available anymore. The Pilot Road used to be perfect for this bike, but no longer avail in 18. I have Pirelli biasply tires on it now. They ride great, but aren't zr rated for the track.
I bought a back wheel on evilbay from a same year gpz1100. Same style, but 17". Any 150 tire will go on (Pilot Road or Dunlop 205). Too bad the 1100 had a larger axle. My 750 bearings won't fit in it either (outer diam too small). I'll call the bearing shop tomorrow to see what they've got, otherwise I'll have to find the axle & swingarm eccentrics from the 1100. Delays, delays.