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).
Tyre clearance issues on a Bentley after fitting larger 6.5 x 17' wheels.
| Identifier | ExFiles\Box 158\1\ scan0144 | |
| Date | 21th October 1937 | |
| S/W. {Sales / Derby Works} Mr. [crossed out] Copy to Rm. {William Robotham - Chief Engineer} Copy to Gx. [crossed out] LES {Ivan A. Leslie} /C/21.10.37. Re Bentley. With reference to your Mx {John H Maddocks - Chief Proving Officer} 10/G12.10.37., Rm. {William Robotham - Chief Engineer} was down here yesterday with an Experimental car fitted with 6.5 x 17" tyres and I borrowed these wheels and tyres and fitted them on a standard Park Ward saloon. We were able to get the car on the bumps in the sandpit and found that both the rear wheels fouled the wheel arches and also the rear body bracket. The front tyres also fouled the front wing stay. I attach two photographs shewing exactly where the rubbing took place on the wheel arch and also I have marked each one with a cross (X) on the rear body bracket where the rubbing took place. It would appear, therefore, that if these larger tyres are to be standardised we shall have to definitely increase the wheel arch clearance. We have not had any case of the standard tyres fouling the wheel arch and measuring a standard tyre and one of the 6.5 x 17" tyres we find there is approximately a difference of 3/8" so that it appears the wheel arch will have to be increased by at least 1/2" each side. J.L.E. | ||