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 India Tyre & Rubber Co. regarding tyre options and load capacities for a Colonial Bentley chassis.
| Identifier | ExFiles\Box 29\4\ Scan252 | |
| Date | 15th December 1934 | |
| HEAD OFFICE AND FACTORY: INCHINNAN, RENFREWSHIRE INDIA TYRE & RUBBER COMPANY LTD. MILEAGE DEPARTMENT (AREA "B") 80 CLAPHAM ROAD LONDON, S.W.9 TELEPHONES: RELIANCE 2662/3 OUR REF. R/WBT. YOUR REF. 15th December, 1934. W.A. ROBOTHAM, ESQ., Experimental Department, Messrs. Rolls-Royce Ltd., DERBY. Dear Robotham, Tyres for Colonial Bentley chassis. With reference to my call upon you yesterday at Derby, when we discussed the possible alternative sizes of tyres which might be fitted to the Bentley for Colonial use. I gathered from our conversation that you were inclined to fit size 5.50-19 cover, which we agreed would raise the car .54". I remember you also told me that the weight of the back axle of the Bentley is increasing slightly; and that you thought the load, including two passengers and luggage, would be slightly over 10-cwts per tyre. In this connection I should like to point out that the maximum carrying capacity of a tyre of 5.50 section is 11-cwts at 36 lbs. The tyres would, therefore, not be over-loaded at that pressure; but I know you will appreciate, if they carry 10 or more cwts. at a pressure of 30 lbs, they would be under-pressured - or if you prefer it, over-loaded. Either over-loading or under inflation are, of course, detrimental to the wearing qualities of the tyre. I only mention this as I know that a pressure of 30 lbs is recommended in your instruction book, and I am not sure if I made this point quite clear during our conversation yesterday. If you should decide to fit 5.50-19 to any chassis for Colonial use, I should be very grateful if you would be so kind as to see that we are given plenty of warning of this decision, in order that we may carry an adequate stock of this size to meet your requirements at our depot in Derby. At the present moment we carry a large stock of 5.50-18 for you, but only a few odd covers of 5.50-19 for ordinary trade purposes. Road Races. I/ | ||