Pirelli Phantoms, that takes me right back.
Back in the late '70s when I got my first proper bike, a Ducati 250 Scrambler, it came to me with worn out/age-hardened 'chunky' semi off-road tyres which I replaced with Phantoms.
IIRC, the choice was Phantom or Mandrake but the Mandrake were not available in the correct size?