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).
Selection of car tyres, their characteristics, and specific sizes for different models.
| Identifier | ExFiles\Box 65\2\ scan0292 | |
| Date | 6th October 1928 | |
| As. from R.{Sir Henry Royce} c. to BJ. Wor.{Arthur Wormald - General Works Manager} c. to C. BY.{R.W. Bailey - Chief Engineer} c. to DA.{Bernard Day - Chassis Design} SG.{Arthur F. Sidgreaves - MD} 7820 R1/M6.10.28. CAR TYRES. X.5820 X.7820 X.4020 We are anxious to use the quietest tyres of the most flexible type (for good low speed riding,) of the smallest wheel diameters (for low appearance of cars) that will give us road clearance. I believe there is some doubt about the life of the Dunlop silent tyres as an effective non-skid. This point should be cleared up. If there is no disadvantage I understand we shall be using : For Phantoms 6 1/2 silents on 21" rims. " 20 HP. 6" " " 20" " " 'SS{S. Smith}' 6 1/2 " " 21" or 20" rims. For India 4.5" " " 19" rims. Not 'Forts', and certainly not 'super-forts'. T. | ||