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).
R.A.C. certificate of performance for a 5,000 miles trial of four Stelastic pneumatic tyres.
| Identifier | ExFiles\Box 1\7\ B001_X15 20 46 50 59-page108 | |
| Date | 9th November 1912 | |
| 235a (150 H) (S.A. 301. 19-2-15) G 0950. X20 9/103 The Autocar. 9th November, 1912. R.A.C. Trial of Stelastic Tyres. THE following certificate of performance has been granted by the R.A.C. in a trial of four Stelastic pneumatic tyres, which took place from September 9th to October 15th: This is to certify that four Stelastic pneumatic tyres were entered for a 5,000 miles trial by Messrs. the Stelastic and General Syndicate, Ltd., of 114-121, Mansion House Chambers, 11, Queen Victoria Street, London, E.C. Description of Tyres.—The carcase of the tyres is of the usual form. The tread is formed of rubber, in which are embedded interlaced upstanding spirals of steel wire. The tyres are of British origin. The tyres were 880x120 mm. The following are the particulars of the tyres: Number. Position on car at start of trial. Weight in lbs. Average thickness of tread, mm. Circumference in inches at 80lbs. per sq. in. after 228 miles. Cross sec. per sq. in. after 228 miles. Before trial. After trial. 110266 Near rear 27¾ 23.5 16.5 108.56 4.24 110558 Off rear 26¾ 23.5 16.5 108.69 4.41 110304 Near front 27½ 23.5 18.0 108.51 4.41 110550 Off front 27¾ 23.0 18.0 109.06 4.31 The tyres were fitted to a 23.8 h.p. (R.A.C. rating) six-cylinder Knight-engined Daimler car. The weight of the car was 1 ton 10 cwts. 1 qr. 17 lbs. (front axle 14 cwts. 1 qr. 20 lbs., back axle 15 cwts. 3 qrs. 25 lbs.). The average load carried was 4 cwts. 2 qrs. 27½ lbs. (of which 2 cwts. 1 qr. 20 lbs., back axle 15 cwts. 3 qrs. 25 lbs.). The average weight 1 ton 15 cwts. 0 qrs. 16¼ lbs. The weather for the greater part of the trial was fine. The trial was held upon the Club's six standard routes (returning to the Royal Automobile Club's garage in London at the close of each day's run), the average speed throughout the trial (running time only) being 19.6 miles per hour. The total distance run by the tyres during the trial was 5,002.5 miles. All four tyres were kept inflated to a pressure of 80 lbs. per square inch. Detachable wire wheels were used. The wheels, with their tyres undisturbed, were changed after 3,500 miles had been run, those upon the back being put upon the front and vice versa. Throughout the trial no puncture occurred, and the covers were not disturbed upon the wheels. Condition after Trial.—The covers were removed after trial and examined. In every case the condition of the casings was found to be very good and without signs of uneven strain. Tyres Nos. 110266 and 110558, which had developed lumps at the sides of the treads about half-way through the trial, were found to have the treads loose in places. Tyre No. 110350 was found to have developed similar lumps. These lumps appeared to be caused by the tread becoming slightly loose upon the canvas casing, causing a quantity of rubber dust to collect beneath the surface. The treads of the tyres were free from cuts. Except in the case of tyre No. 110304, which had a small hole through the casing, there were no signs of perforations through the covers. | ||