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 different tyres on a Bentley chassis B.23.AE, measuring telescope readings and slip angles at various speeds.
| Identifier | ExFiles\Box 156\3\ scan0048 | |
| Date | 13th April 1938 | |
| DATE OF TEST 13.4.38 TYRE COMPARISONS ON BENTLEY CHASSIS B.23.AE. All 6.50 x 16 tyres on 4.500 rims. All tyres at 28 lbs/sq.in. pressure. All 6.50x17 tyres on 4.000 rims. | Tyre. | Speedometer speed. | Telescope Reading. 1st.test. | 2nd.test. | 3rd.test. | Average. | Slip angle. | |------------------|--------------------|------------------------------|-----------|-----------|----------|-------------| | India 6.50 X 17 6 ply. | 4.0 | 0.30 | 0.40 | 0.40 | 0.37 | - | | | 19.4 | 2.20 | 2.30 | 2.30 | 2.27 | 1.50 | | | 24.2 | 4.00 | 4.10 | 4.00 | 4.03 | 3.36 | | | 29.0 | 6.10 | 6.20 | 6.30 | 6.20 | 5.43 | | Avon 6.50X17 4 ply | 4.0 | 0.30 | 0.35 | 0.30 | 0.32 | - | | | 19.4 | 3.00 | 2.55 | 3.00 | 2.58 | 2.26 | | | 24.2 | 5.20 | 5.10 | 5.20 | 5.17 | 4.45 | | | 29.0 | 8.30 | 8.10 | 8.25 | 8.22 | 7.50 | | Avon 6.50X17 6 ply. | 4.0 | 0.40 | 0.35 | 0.40 | 0.38 | - | | | 19.4 | 3.00 | 3.00 | 3.00 | 3.00 | 2.22 | | | 24.2 | 4.30 | 4.30 | 4.40 | 4.33 | 3.55 | | | 29.0 | 7.10 | 7.10 | 7.00 | 7.07 | 6.29 | | India 6.50X16 6 ply. | 4.0 | 0.40 | 0.35 | 0.40 | 0.38 | - | | | 20.4 | 2.50 | 2.40 | 2.50 | 2.47 | 2.09 | | | 25.5 | 4.40 | 5.00 | 5.00 | 4.54 | 4.16 | | | 30.5 | 8.00 | 8.05 | 8.10 | 8.05 | 7.27 | | Avon 6.50X16 4 ply. | 4.0 | 0.30 | 0.30 | 0.40 | 0.33 | - | | | 20.4 | 3.30 | 3.20 | 3.20 | 3.23 | 2.50 | | | 25.5 | 5.30 | 5.50 | 5.40 | 5.40 | 5.07 | | | 30.5 | 9.30 | 9.40 | 9.40 | 9.37 | 9.04 | | Fisk 6.50X16 4 ply. | 4.0 | 0.40 | 0.30 | 0.30 | 0.33 | - | | | 20.6 | 2.40 | 2.40 | 2.40 | 2.40 | 2.07 | | | 26.0 | 4.45 | 4.30 | 4.45 | 4.40 | 4.07 | | | 31.0 | 8.00 | 8.10 | 8.00 | 8.03 | 7.30 | On Fisk tyres 20.6 m.p.h. = 0.24 g.{Mr Griffiths - Chief Accountant / Mr Gnapp} 26 m.p.h. = 0.36 g.{Mr Griffiths - Chief Accountant / Mr Gnapp} 31 m.p.h. = 0.48 g.{Mr Griffiths - Chief Accountant / Mr Gnapp} | ||