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).
Performance and characteristics of larger tyres on a Phantom III vehicle.
| Identifier | ExFiles\Box 157\2\ scan0223 | |
| Date | 12th January 1938 | |
| Get new mould 1332 S/W. Rm.{William Robotham - Chief Engineer} Larger Tyres- Phantom III. Cx{Major Len W. Cox - Advertising Manager}8/KW12.1.38. Reference Rm{William Robotham - Chief Engineer}/Gryl/MHL1.1.38, I have been using a set of these larger tyres on 3-BU-190 since just before Christmas, and they were on the car when you tried it for lamps on Monday night last. I have not so far noticed any objection to them from the point of view of clearance. The steering, though possibly slightly heavier than it was before, is still very conveniently light and very pleasant to handle. Their road adhesion is definitely better than the standard tyre, which is very weak in that respect I think when used on the wood block roads in London. Their silence is not bad, that is to say, they are not quite as silent as the present standard tyre when new, but as the present standard tyre gets very noisy at about 4000 there probably is not very much in this. I am running the pressures at 35 lbs the same as for the standard 7" tyres, and there is no difference to which one could ordinarily take any exception in the comfort of the ride. Probably you were unaware of the fact that my car was fitted with these bigger tyres when you tried it on Monday last. It is difficult to believe that only 10% improvement in mileage will result, but time will tell whether that is so or not. The noise, or sing, to which you refer will I understand disappear when Dunlops produce the proper mould having variable pitch arrangement at the walls of the tyre, and I believe they are going ahead making a mould to produce tyres for us of this size to the latest accepted pattern. If we do not propose to use the bigger tyres we ought to stop Dunlops making the mould unless they want it for other people as well, but personally I am hoping we shall adopt the bigger tyres if only because of the better adhesion, as I have not yet found any drawbacks to them. Cx.{Major Len W. Cox - Advertising Manager} Hives | ||