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 Dunlop Rubber Co. discussing the implications of smaller diameter wheels and tyres on tyre mileage for the 20 HP car.
| Identifier | ExFiles\Box 45\2\ Scan026 | |
| Date | 13th April 1927 | |
| C O P Y. DUNLOP RUBBER CO.LTD+ FORT DUNLOP, ERDINGTON, BIRMINGHAM. 13th. April. 1927. Messrs. Rolls-Royce Ltd., Derby. For the attention of Mr. W. A.{Mr Adams} Robotham. Dear Sirs, We have your letter of the 12th, and note your remarks with regard to diameters of wheels and tyres for your 20 HP. car. We are aware of a very considerable movement in America towards the adoption of smaller diameter rims and tyres, and we already have in hand the production of a considerable range of tyres to fit both 18" and 19" rims. Tyres in these sizes we shall have to supply for replacement purposes, but we have not taken the initiative in offering these smaller dia. tyres to British car makers because whatever may be the advantages of these small wheel diameters from the point of view of car design, they are certainly not good from a tyre performance point of view. A reduction of 2" in wheel dia. means a very considerable reduction in tyre mileage - in fact a reduction of as much as 30 to 35%. Actually we have information that already some American tyre manufacturers are finding tyre mileages on 18" rims reduced to 60% of the mileage hitherto obtainable. Of course, the obvious thing is that in reducing tyre dia., the section should be increased to provide equivalent tyre capacity, but unfortunately this does not make good the loss of mileage resulting from reduction of diameter. The writer would be very glad to go into this matter in more detail with you at any time to suit your convenience, and we shall of course supply you with some sets of tyres on 19" rims to enable you to make your own observations, but we find that that size will not be ready for a few weeks. However, we shall be able to give you a 6" tyre on an 18" rim very shortly after the holidays. That might in the meantime be of some interest to you. Yours faithfully, FOR THE DUNLOP RUBBER CO. LTD., W. H.{Arthur M. Hanbury - Head Complaints} Paull - sgd. | ||