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).
Comparison of performance between balloon and cord normal tyres, detailing acceleration, speed, and hill climb tests.
| Identifier | ExFiles\Box 53\2\ Scan056 | |
| Date | 13th September 1923 | |
| X4565 BALLOON AND CORD NORMAL TYRES. Acceleration and speed comparisons. Car used - 6-Goshawk-11. Weight with passengers 1 ton. 11 cwts. 2 qrs. Road surface dry - wind gusty. Axle 11 X 50 = 4.545 direct ratio. Tyre conditions. Balloon inflation 15 lbs./sq.in. all round - Circumference 99¾" effective. Spenwood cord 45 lbs. rear, 40 lbs. front - Circumference 102¼" effective. Speed and Acceleration. Taken both ways, mean of several readings correct for different tyre circumferences, - Mean distance - 708 yds. | | Starting speed. | Finishing speed. | Time. | Equivalent mean speed. | Equivalent mean acceln. | |---|---|---|---|---|---| | Spenwood cord. | 20 | 55.5 | 36 | 40 | 1.45 f.p.s² | | Balloon tyres. 15lbs/in² | 19¼ | 54 | 37½ | 38.5 | 1.36 " | Test on Standard Hill. | | Start. | Max. | Min. | Finish. | Time. | |---|---|---|---|---|---| | Spenwood cord. | 9.25 | 41.75 | 21.75 | 28 | 1 min. 47½ secs. | | Balloon tyres. 20lbs/D° | 9.75 | 41.5 | 21.75 | 28.25 | 1 " 46 " | | ||