This blog, in addition to the usual maintenance details for classic mini cars, an attempt is made to explain the "whys" and "wherefores" of the various jobs.

Saturday, 17 October 2009

Tyre Pressure Checks

It is essential to use an accurate pressure gauge when checking the tyre pressures (which are listed in the Appendix) and to protect it from knocks and grit when it is not in use. Garage airline gauges are not always accurate.

Whenever pressures are checked, make sure that the valve caps are replaced and tightened firmly. These are intended to prevent leakage and at the same time exclude mud, grit and ice from the relatively vulnerable inner seals. If a cap should be lost a replacement should be fitted as soon as possible.

If the tyres are fitted with inner tubes, pressure will be lost at the rate of from 1 to 3 lb per week, owing to a process known as "diffusion."

Oxygen from the air in the tyre is absorbed by the rubber and a corres¬ponding amount of oxygen is given off from the outer surface of the tube. It is necessary, therefore, to restore this slight loss of pressure even when the tubes are in first-class condition. Synthetic rubber tubes and tubeless tyres do not suffer from this disadvantage but it is still advisable to check the pressures regularly.