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).
Wheel and tire specifications, including clearance, spoke count, and issues with drop center rims.
| Identifier | ExFiles\Box 42\4\ Scan169 | |
| Date | 22th August 1930 guessed | |
| - 2 - Clearance from brake drums and cross steering tube is obtained by offsetting the wheel on the hub 1/2" more than present standard as recommended by Mr. Hives. The standing height of the wheel with U.S. Royal Cord Extra Heavy S.S. tires at 35 lbs. is about 15-3/8" and the rolling diameter about 31.5". The wheels have 78 spokes instead of 84. No change to hubs. Parking, shimmy, etc. are distinctly better than 21" wheels. The complete wheel and tire weighs 77 lbs. Drop Center. Drop center rims cannot be used in this size without fouling the cross steering tube unless the wheel offset is further increased. Our experience on D.C. rims so far has been unfortunate. We have had a lot of trouble with tubes cutting due to friction against the "toe" of the bead, and find the tires extraordinarily difficult to mount and remove. At present the drop center movement seems at a standstill in the U.S. All manufacturers except Ford use the straight side tire. Yours faithfully, ROLLS ROYCE OF AMERICA, INC. Maurice Olley Encl. A-12177 [Illegible stamp text] RECEIVED JO ASA H² | ||