Increased Mileage on Pneumatic Tyres with Decreased Pressure.

Progress, Volume IV, Issue 2, 1 December 1908, Page 49

Increased Mileage on Pneumatic Tyres with Decreased Pressure.

On this subject, to which we devoted, recently, considerable space, the well-known Mr. S. F. Edge writes :— Sir, — As you are probably aware, I have made very considerable experiments to find out, firstly, whether reduced pressure decreases the speed of the vehicle fitted with pneumatic tyres or not, secondly, whether decreased pressure decreases or increases the life of the tyre. The first series of tests prove that reduction of pressure in the tyres makes practically no difference in speed. The second series of tests prove that you can use your tyres with less pressure than was commonly thought, and, therefore, the whole car rides more easily and smoothly,

and at the same time the tyres actually last longer. The tests have all been carried out on the road on my own six-cylinder Napier. The weight of the car complete, as I generally drive it, was a shade under 35 cwt. The result was that with 601bs. pressure in the front tyres (880 x 120) they ran 88 per cent, further than when the pressure was kept at 701bs. to the square inch, and when the pressure of the back tyres (895 x 135) was reduced from 851bs. to 701b5., I got an increased mileage of 49.9 per cent. It is, therefore, clearly proved that reduced pressure means greater comfort on a motor car and less expense in tyre bills. I am now carrying out experiments with still lower pressures, but owing to the distance one has to run, it takes a considerable time to obtain results.