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 discussing tyre sizes, wheel balancing, and gear ratios for a vehicle.
| Identifier | ExFiles\Box 90a\6\ Scan056 | |
| Date | 11th August 1936 | |
| Page 2. W. A.{Mr Adams} Robotham Esq., 11th August, 1936. If we decide that a tyre change will be necessary, the amount of petrol can be put in to suit thus giving some advantage in regard to starting weight. We have agreed with Mr. Hall that the size of tyres to be used will be 6.00/19 front and 6.50/19 rear. He has suggested that he would like to use 7.00/19 tyres and we have made some tyres for trial in the practice runs and possibly in the race and told him that we will tell him definitely before the race whether we recommend his using these. I have looked into the question of using a smaller diameter rim to keep the centre gravity of the car down but I am afraid that we cannot get the gear ratio to suit even having regard to the 10% higher gear ratio in the special back axle which you mentioned on my visit to Derby. I would like you to confirm that these arrangements meet with your approval and if there are any points on which you do not agree, we would be pleased to hear from you. We have despatched 5 - 6.00/17 tyres, tubes and wheels to Mr. Sleator at the Franco Britannic Autos. Unfortunately, as you know, Bramber did not leave sufficient space for the accommodation of the balance weights. We, however, managed to get weights fitted in and so balance the wheels and tyres which were sent to Mr. Sleator. We have a letter from your Mr. Grylls enclosing a print G.B. 2397 showing a modification to the spoking to accommodate the balance weights. We think that it would be quicker to have new wheels made to suit rather than try to alter the wheels which you have. I will get in touch with the Bramber Engineering Company in regard to this matter. - Continued - | ||