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).
Tyre pressures provided by Michelin and proposing new additions for specific axle weights.
| Identifier | ExFiles\Box 39\2\ Scan119 | |
| Date | 29th October 1921 | |
| W/S X3538 Sp.{Mr Spinney} from Hs.{Lord Ernest Hives - Chair} Hs{Lord Ernest Hives - Chair}3/LG29.10.21. TYRE PRESSURES. X3538 The tyre pressures given by the Michelin people are very interesting because they appear to be in agreement with the pressures we require. We recommend that you get the Michelin people to approve of tyre pressures suitable for the 150 diameter tyres which we use. In their list they give the following pressures:- Axle weight. Tyre pressure. 35 cwts. 75 lbs. 32 " 65 " 30 " 60 " Our average car with two passengers weighs approx. 20 cwts. on the front and about 23 cwts. on the rear. We should like the Michelin Co. to agree to the following addition to their list:- Axle weight. Tyre pressure. 28 cwts. 55 lbs. 25 " 50 " 23 and under 45 lbs. We should also like to know from the Michelin people whether the pressures they give are with the tyre cold or with the tyre at its normal temperature. There is a considerable increase in pressure as the tyre gets warm. If we could only get a definitely agreed pressure from the Michelin people, then we could use it as the leader [handwritten: lever] to bring the other tyre makers into line. Hs.{Lord Ernest Hives - Chair} | ||