From the Rolls-Royce experimental archive: a quarter of a million communications from Rolls-Royce, 1906 to 1960's. Documents from the Sir Henry Royce Memorial Foundation (SHRMF).
Letter reporting on the performance, mileage and specifications of Super-cushion tires.
| Identifier | ExFiles\Box 53\2\ Scan027 | |
| Date | 4th August 1923 | |
| Oy2-N-3425 August 4, 1923. Mr. Claude Johnson, Rolls-Royce, Limited, London, England. (Copy for attention of Mr. Royce Mr. Platford Mr. Hives) Dear Sir: Re Super-cushion Tires In our letters of March 9 and March 14, addressed to yourself with copy for the attention of Mr. Royce, we mentioned the 32x6 tires fitted experimentally to one car at the factory, and sent photographs of these and of the 33x5 tires on my own car. We also sent actual prints showing contact areas of tires and floor. We wish to notify Mr. Royce that these tires have now completed 10,600 miles on this car, and the diamond tread is not yet worn smooth in the centre, so that evidently the tires are good for a total of 15,000 to 20,000 miles. This is twice the best mileage on the rear wheels of the best American 33x5 tires under our road and driving conditions, as proved by previous tests of several makes on the same car. The only troubles with these tires in all this period were three punctures from nails. They were run between 35 and 40 lbs. pressure. The 32x6 tire, however, is only 31.8" rolling diameter, instead of 34" for the 33x5, and therefore reduced the road clearance by 1.100 inches. We are therefore getting a sample set of 34x7 tires which will fit on the same rims as the 32x6, and will report their behaviour at an early date. The 34x7 is the counterpart of the 33x5 as regards rolling diameter and road clearance, and the only changes necessary in body construction would be a reduction in width at the rear. | ||