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).
Proposing the adoption of Low Pressure Tyres and a simplified range of substitutes for various car models.
| Identifier | ExFiles\Box 53\2\ Scan045 | |
| Date | 21th August 1923 guessed | |
| 8. different types of tyre made for one and the same type of car is an admission that nonne "Best" tyre has yet been adopted. The adoption of the Low Pressure Tyre principle might appear tardy but such is not the case, when it is realized that but for the modern multiple Cord casing construction large sections were not feasible. The time is opportune therefore to get right away from old troubles and start afresh and adopt a simple range of tyres which will fill all requirements but at the same time reduce stocks to be held and thus lead to a reduction in the cost of motoring even apart from any inherent superiority of the Low Pressure Tyre as compared with normal tyres. Such a new range should allow of oversizing at will and to a greater extent than is possible with existing rims and tyres. Popular sizes as in regular use today and proposed substitutes work out as follows:- Existing sizes. Popular. S/E M/M Substitute. Oversize. Heaviest cars 40 HP. Medium dia. 33 x 5 895x135 36x6 no oversize. Heavy " 20 HP. Large dia. 34 x4½ 880x120 Small dia. 32x 4½ 820x120 34 x 7 36 x 8 Medium Cars 15 HP. Large dia. 34 x 4 875 x 105 small dia. 32 x 4 815 x105 32 x 6 34 x 7 Light Cars 10 HP Large dia. 30 x 3½ 760x90 } Small dia. 28x3½ 710x90 } 30 x 5 - Small Cars 8 HP. 26 x 3 700x80 27x4½ - Such a range substitutes 5 sizes for 16 ditto 1 type for 2 The obvious comment on such a range will be that it does not allow for two diameters for each size of car excepting by over-sizing with a heavier or more expensive tyre. This is true but it should be realised that the low Pressure tyre provides that extra cushion which it is sought to provide with normal tyres by fitting large diameter wheels but to a much greater degree than is practicable by such means. Therefore it is not necessary or desirable to introduce two diameters of each different section. | ||