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).
Data table comparing turning circles and lock angles for various tyre and rim configurations.
| Identifier | ExFiles\Box 158\1\ scan0183 | |
| Date | 11th May 1938 guessed | |
| Fixed out-of-centre point. for 2.17" out-of-centre 41° lock angle inside wheel. Given Turning Circles. Tyres. Size. | Rim Dia. | Rim Width. | Lock Angle Outside Wheel. | Turning Circle B.III. | Turning Circle B.50. | Out-of-Centre | Outside Wheel Lock Angle for 41° lock angle inside wheel. | Turning Circle B.III. | Turning Circle B.50. 6.50" | 16.00" | 4.50" | 29° | 40.45' | 42.45' | 2.80" | 31¹/₃° | 39 | 41. | | | | | | 2.38" | 29²/₃° | 40 | 42. 6.50" | 17.00" | 4.50" } | 30° | 39.81' | 41.81' | 2.50" | 31¹/₃° | 39 | 41. 7.00 | 17.00" | 4.50 } | 7.00 | 16.00 | 5.00 } | 28° | 41.12' | 43.12' | 3.00" | 31¹/₃° | 39 | 41. 7.00 | 17.00 | 5.00 } | | | | 2.58" | 29²/₃° | 40 | 42. | | | | | | 2.27" | 28¹/₃° | 41 | 43. 7.5 | 16.00 | 5.00 | 27¹/₆° | 41.76' | 43.76' | 3.12" | 31¹/₃° | 39 | 41. | | | | | | 2.70" | 29²/₃° | 40 | 42. | | | | | | 2.40" | 28¹/₃° | 41 | 43. Bentley II Turning Circle 39'7" L.H. 40'11" R.H. Phantom III " " 48' L & R.H. Wraith III " " 44' L & R.H. 25/30 HP. " " 42' L.H. 47'5" R.H. The figures for B.II, P.III & 25/30 are obtained from the Instruction Books and also from the "Autocar" - the same figures occuring in both places. The Wraith III figure is one measured on the skid pad (one car only) and the calculated figure is 42'7". | ||