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 to Vauxhall Motors regarding tyre specifications, comparing 4-ply and 6-ply tyres for comfort and steering.
| Identifier | ExFiles\Box 170\3\ img182 | |
| Date | 22th December 1938 | |
| Rm{William Robotham - Chief Engineer}/Gry.{Shadwell Grylls}10/MH.{M. Huckerby} 22nd. December 1938 M.{Mr Moon / Mr Moore} Olley, Esq., Vauxhall Motors Ltd., Luton, BEDS. Dear Oy., Many thanks for your letter about 4-ply tyres. There are still one or two points we do not understand; and on the principle that "those who don't ask don't get", we send them herewith. Firstly, on what grounds do the Tyre & Rim Association limit 4-ply tyres of 6", 6.5", 6.75" sections to 28 lbs/sq.in. and the corresponding load. Six ply tyres are allowed more inflation and a greater load. If the tyres for a car are chosen on a cornering power basis our skid pan figures show that a 6-ply tyre of a given size has greater cornering power than its 4-ply counterpart, even when inflated to give the same comfort. One can, therefore, choose say, a 6-ply 6.5" tyre or a 4-ply 7" tyre. The comfort will be much the same, the weight much the same, but the steering heavier with the larger tyre. Which would you use for an axle load of 1150 lbs ? I should like to educate the British public to have smaller tyres by 1/2" in front than at the back (fitted to the same wheels, of course). One never keeps the spare on for more than a day. The advantages would be lighter steering and even wear front and rear. What are your views ? Yours sincerely, P.S. I have a memory that the U.S.A. is plastered with advertisements of Lifeguard tubes. Is this a thing of the past ? | ||