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).
Proposed new range of low-pressure tyres, their specifications, and fitting considerations for older chassis.
| Identifier | ExFiles\Box 53\2\ Scan046 | |
| Date | 30th August 1923 guessed | |
| 9. Originally the Writer proposed to advocate making each size of tyre in two weights so that a 34 x 7 tyre could be substited by a Light 36 x 8 but further experience goes to show that the great riding improvement provided by Low Pressure Tyres makes such a plan unnecessary. Table No....shows to scale and in figures how the proposed range compares with existing standards when considered from the "Gear" point of view , namely as regards "effective " dia. The proposed range of tyres conforms very closely when new to the size marking as regards outside diameter and section width. In motion the new tyres do not deflect existing springs so much as normal tyres, therefore the increased diameters do not affect wing clearance as regards diameter. Lateral wing clearance is seldom a trouble in fitting to old chassis. The points which require watching are clearance for outside brake gear on back hubs and for forward steering rod when steering is in right hand full lock. | ||