Lotus 7 in F1 ?
www.lotus7register.co.uk/springbk.htm shows Niemann's 1958 Lotus 7
(it got 10th place in the 1962 Rand GP (no not the South Africa GP), slipstreaming Lotus 25s at 127 mph)
the register seems to say that later cars had tyres as wide as 5.20" 130 mm