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 discussing the results of experiments on effective tyre radius at various speeds.
| Identifier | ExFiles\Box 45\1\ Scan338 | |
| Date | 25th June 1925 | |
| Telegraphic Address, "DUNLOPS, BIRMINGHAM" Telephone No. BIRMINGHAM CENTRAL 4108. PRIVATE BRANCH EXCHANGE. 25 LINES. Registered Offices, DUNLOP HOUSE, I, ALBANY ST.{Capt. P. R. Strong} LONDON, N.W.I. BY APPOINTMENT DUNLOP RUBBER CO LTD. Founders of the Pneumatic Tyre Industry FORT DUNLOP, ERDINGTON, BIRMINGHAM. STATION: CASTLE BROMWICH, (MID. RY.) GOODS: TO DUNLOP SIDINGS, CASTLE BROMWICH. CAR ROUTE: TYBURN ROAD FROM STEELHOUSE LANE. TO FORT DUNLOP WORKS, CAR 63. WHEN REPLYING PLEASE QUOTE ON BOTH LETTER & ENVELOPE Research Department. ALL COMMUNICATIONS TO BE ADDRESSED TO THE FIRM Handwritten text: X4650 Messrs. Rolls Royce Limited, Nightingale Road, DERBY. 25 June 1925. Your ref: Hs{Lord Ernest Hives - Chair}/Rm{William Robotham - Chief Engineer}1/LG. Dear Sirs, Effective Tyre Diameter at High Speeds. Further to our letter of the 20th., we have now made some experiments to determine the effective radius of our 33 x 5 tyre at various speeds. Unfortunately we have no facilities at the moment for testing at speeds higher than 50 miles per hour, except on the racing track, where the conditions render it almost impossible to obtain data. In the near future we hope to have completed a new machine capable of much higher speeds than those you mention. The curve attached shows the increase in radius in millimetres at all speeds up to 50 miles per hour, and by extrapolation it is estimated that in the range 70 to 90 miles per hour the increase will be from 5 to 8 mms. It is noteworthy that the increase is roughly proportional to the square of the speed. | ||