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 from the India Tyre & Rubber Company discussing experiments on a new tyre tread pattern for the Rolls-Royce Bentley Chassis.
| Identifier | ExFiles\Box 29\4\ Scan126 | |
| Date | 9th August 1933 | |
| x+62. INDIA TYRE & RUBBER COMPANY (GREAT BRITAIN) LTD. TELEPHONES PAISLEY 4141/5 INCHINNAN SCOTLAND TELEGRAMS INDIAOWL, RENFREW. OUR REF. HSC/JT YOUR REF. 9th August 1933. Messrs. Rolls-Royce Ltd., DERBY. For attention of W.A. Robotham Esq., Dear Sirs, In the course of the experiments which we have conducted with a view to finding the most suitable tread pattern for the Tyre to be fitted to the Rolls-Royce Bentley Chassis we devised a tread which basically is very slightly different from that which has already been tested and approved by you. These same experiments have also been conducted with a Tyre of which the tread is composed of even spaced blocks; this in order to ascertain whether there is any real advantage, from the point of view of silence, in the uneven spaced blocks. We have made a mould of this modified design which differs from that which you know already with the exception of the even spacing of the blocks in that the centre rib has been reduced in width by about 1/32" whereas the shoulder ribs have been increased by exactly the same amount as we have taken from the centre rib. The tread surface in contact with the road is exactly the same as that of the Tyre which has already been submitted to you, of which, however, we felt that the centre rib was possibly slightly too wide to give the utmost flexibility that could be obtained from the Tyre. The angle of the two grooves which run circumferentially round the Tyre has also been slightly changed in order to avoid too much gaping when the Tyre is under pressure. On tests undertaken by us with the Tyre which is being sent to you we find very little difference as regards silence, and rather better wearing qualities, particularly on the front wheels, and a still greater degree of flexibility due to the reduction in width of the centre rib. You know that the moulds for the 'Speed Special' Tyre are only | ||