NORMAN SMITH’S TYRES.

Matamata Record, Volume XIII, Issue 1104, 10 March 1930, Page 5

NORMAN SMITH’S TYRES.

During its appearances on the Ninety Mile Beach, the 500 h.p. R tlls-Royec-Cadillac car in which Mr Norman, “Wizard” Smith established a new world’s record for 10 miles, and raised the Australian and New Zealand mile j record, attracted a great deal of attention, and much of this was centred on the tyres. The most Striking feature was the total absence of any .tread, the tyre being absolutely smooth, without any pattern. The result was that when the car was travelling at its highest speed, it left tracks no wider than those of a racing motor-cycle, the whole weight of the car being carried on a strip in the centre of the tyre, not two inches wide. The smooth surface of the rubber and the absence of any protuberances prevented any drag on the wet sand, and it was estimated at the time that-there was less than 1 per cent, loss of efficiency from this or any other cause. Another striking feature of the tyres, which were specially made in an American factory for the ear, was the extreme thinness of the outer layer of rubber, which did not exceed an eighth of an inch. In one or two places on one of the tyres, which was changed before the second record was set up, cuts from shells less than an eighth of an inch deep exposed the fabric. There were ten plies of rubber and fabric, which instead of being woven from cotton fibre, was of twisted silk to withstand the heavy strain which was placed on it. The tyres were designed to be ruri with pressures of from 85 to 1101 b. to the square inch. When the records were made, the tyres were inflated at a pressure nearer the lower end of the range of pressures under which they would run satisfactorily.