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).
Test report comparing Rapson Cord Tyres (33 X 6.75) against Dunlop tyres for noise, comfort, and steering wobble.
| Identifier | ExFiles\Box 39\1\ Scan197 | |
| Date | 11th July 1928 | |
| Y3536 S/2aRa 11.7.28. RAPSON CORD TYRES (33 X 6.75). A set of the above tyres have been tested for noise and general efficiency with the following results :- NOISE. Noises at high speeds are not very great, the note of the noise is lower than the triple stud tread Dunlop and varies in intensity as the wheel passes over uneven patches in the road. On a really level good road the noise is slight. At low speeds the tyres groan rather badly, between 10 and 20 m.p.h. This effect is especially noticeable on a heavily tarred road on a hot day when the tar is soft. On a rough metalled road the noises are not noticeably bad. RIDING COMFORT. It is not possible to detect any difference in riding comfort between the Rapson and standard Dunlop tyres at equal pressures. HIGH SPEED STEERING WOBBLES. The Rapson tyre fitted with the deflector tube is superior to the Dunlop. Tests were carried out on chassis 17-EX with axle control damping only. With Rapson tyres very slight wobbles were produced between 60 and 70 m.p.h. with both front wheels 0.5 lbs. out of balance and 30 lbs/sq.in. tyre pressure. When using Dunlop tyres a more severe wobble was produced between 60 and 70 m.p.h. with the wheels 0.5 lbs out of balance but with a tyre pressure of 40 lbs/sq.in. (Under these conditions no wobbles occur with Rapson tyres). Possibly the Rapson tyre is superior in this respect owing to its heavy weight - viz : Rapson outer cover 41 lbs. Dunlop " " 32.5 lbs. Rapson deflector tube 9.75 lbs. Dunlop tube. 5 lbs. Rapson ordinary tube 5 1/4 lbs. SKIDDING. Since receiving these tyres there has been no wet weather, consequently we cannot give any comments on their anti-skid qualities. Hs{Lord Ernest Hives - Chair}/A.J.Lidsey. | ||