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).
The performance of Balloon Tyres after mileage testing, including conclusions on skidding and braking.
| Identifier | ExFiles\Box 53\2\ Scan085 | |
| Date | 21th January 1924 | |
| R.R. 493 A (40 H) (SL 42 12-7-23). J.H., D.{John DeLooze - Company Secretary} 4565 EXPERIMENTAL REPORT. Exptl. No. 4565 REF: HS{Lord Ernest Hives - Chair}1/LG21.1.24. To R.{Sir Henry Royce} from Hs.{Lord Ernest Hives - Chair} c. to CJ. RG.{Mr Rowledge} c. to DA.{Bernard Day - Chassis Design} E.{Mr Elliott - Chief Engineer} c. to BY.{R.W. Bailey - Chief Engineer} OY. BALLOON TYRES. We have now completed approximately 6000 miles with the 32 X 7" tyres on a 20 HP. and about 3,000 miles with the 32 X 8" tyres on a 40/50 HP. car. We have recently had a visit from the Technical representatives of the Dunlop Rubber Co. and it has been agreed that they will replace the 32 X 7" for the 20 HP. 32 X 6", and will replace the 32 X 8 by 32 X 7" tyres for the 40/50 HP. car. From experience of running Balloon tyres we have arrived at the following conclusions. (1) When the tyres were new we made comparative tests and found that they were considerably better than the standard tyres for preventing the car skidding sideways, i.e., if the brakes were applied, the wheels would skid in the ordinary way, but the car would continue on a straight course. We attribute this to the fact that on the Balloon tyres the width of the tread is the same as a normal tyre and it has a longer length of tread in contact with the road and therefore a non-skid pattern would have more abutments to prevent side-slip. When the tread has worn smooth there is no advantage whatever in Balloon tyres over the standard tyres with smooth treads. In fact, it is possible that on certain road conditions the harder tyre might grip the road better. (2) As regards braking. We have carried out comparative tests and can find no advantage in braking on ordinary contd:- | ||