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).
Letter providing recommendations on tyre pressure for straight-side cord tyres.
| Identifier | ExFiles\Box 39\2\ Scan124 | |
| Date | 14th November 1921 guessed | |
| Messrs. Rolls-Royce, Ltd. - 4 - friction than the fabric carcass construction. And, Straight-side cord tyres may also appear to permit of being operated at relatively lower pressures with safety, for the reason that in practically all cases they have to date been made bigger than the theoretically equivalent metric fabric tyre. In the case of your own test work, wherein you probably check the tyre pressures every day, and maintain uniform pressure throughout the life of the test, you unquestionably are justified in maintaining slightly lower pressure than you would be justified in recommending the Rolls-Royce user. We would like to suggest that you recommend that your users maintain pressure of at least 10 to 20 lbs. more than those you have mentioned in your letter, and that you impress upon them the importance of never letting the pressure get any lower. In order to check their pressure correctly, they must, of course, have a proper tyre pressure gauge, like the Schrader, and we frankly believe that you will find it worth while to include such a gauge with each car, or chassis, that you deliver, and that you make mention of the importance of using it -- to ensure satisfactory tyre mileage -- in the instruction booklet which possibly accompanies each car. Even the pressure which you will get from adopting the suggestion just above mentioned will perhaps not be adequate for all Rolls-Royce cars, for we have known of some cases where extremely heavy special bodies have been fitted for which even 5" straight-side cord tyres, inflated to maximum pressure, would scarcely be sufficient. In brief, then, as you probably have already concluded, I have found it, as I feared, rather awkward to express | ||