The 18" prototype tyres look wonderful.. It seems Pirelli have chosen a relatively narrow tread width relative to the nominal width, and there the tyre appears slightly stretched on the rim, as is the modern fashion.
It is a shame the wheels will be covered. Ironically, the OZ 18" F1 wheels look a bit like the iconic Turini wheels from rival wheel manufacturer Speedline.
The wheels will be a control part if I understand right? No more Apptech, Enkei, BBS or Rays wheels in F1 (albeit the latter two have quit long ago AFAIK), which is a shame. Most of the teams are currently supplied by OZ anyway, and removing the wheels as an avenue for aerodynamic / tyre temperature development is prudent.