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 from the India Tyre & Rubber Company detailing the weights of various tyre tubes and recommended rim sizes.
| Identifier | ExFiles\Box 30\5\ Scan051 | |
| Date | 22th March 1935 | |
| Cont.....3. W.A. Robotham, Esq. 22nd March, 1935. We give you below the weight of India tubes in different sizes as this may be of some help to you in considering the weight question. Weight (lbs.) 5.50-18 W.B. 3.48 6.00-16 W.B. 2.55 6.50-16 W.B. 2.70 7.00-16 W.B. 3.90 Thus you will see that the 5.50-18 India Speed Special cover and tube weighs 30.00 lbs. and the 6.00-16 4 ply cover and tube weighs 23.58 lbs. I note that you found that the Essex tyre, tube and wheel assembly was about 56 lbs. per set lighter than the 5.50-18 as fitted to the Bentley. The above figures show a difference of 25.68 lbs. per set of covers and tubes and the rest of the difference must be in the rim, spokes and hubs, namely, about 7.6 lbs. per wheel, which seems reasonable in view of the different type of construction. The standard rims for which the Aero Cushion tyres are designed are as follows:- Recommended. Permissible. 6.00-16 4.00 D - 16 6.25-16 4.50 D - 16 4.00 D - 16. 6.50-16 4.50 D - 16 4.00 D - 16. 7.00-16 5.00 E - 16 4.50 D - 16. We should be pleased to hear further from you regarding this matter as we are most anxious to help you in any way possible. Yours faithfully, INDIA TYRE & RUBBER COMPANY LIMITED. Paul Worth. Works Manager. | ||