Ten years ago take-off speeds rarely exceeded 130 m.p.h. and the maximum inflation pressure used in aircraft tyres was about 120 lb./in2. Today tyres have to cater for speeds up to 230 m.p.h. and pressures of 350 lb./in.2. The increased requirements have produced serious problems of heat generation within the tread and carcass of tyres, which, if not solved, result in disintegration. Fig. 1 shows the effect of speed on tyre temperature and also, the effect of lightening the tyre construction.

Beyond the speed range shown, the temperature rises rapidly and tyre failures would occur. To meet these conditions, improved materials with lower hysteresis losses, and capable of operating at higher temperatures, have been produced. Control can also be obtained by modifying casing cord angles, reducing casing and tread thicknesses and so on.