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Self inflating tires are not readily available for the majority of vehicles. The military and some commercial vehicles are fitted with them along with the Hummer. The Hummer is famous for being Arnold Schwarzenegger’s “new baby”.
Tires deflate through normal use and they can lose pressure during changes in the weather. We should test our tire pressure regularly using a pressure gauge. By the time under inflation is obvious to the eye, the tires could be extremely unsafe on the road. Tires affect the cars capability to turn corners and stay on the road, and driving with under or over inflated tires can cause faster tire wear and less economical fuel consumption.
There are only a few different self inflating tire systems that are in use, these are designed for performance and slow tire punctures but not for flat airless tires.
The central tire inflation system (CTIS) is designed to inflate or deflate tires automatically, this is necessary for optimum performance. Tires need more air while driving on hard surfaces at high speeds and less air for driving on soft surfaces such as soil or sand.
The driver of the vehicle will select an appropriate tire pressure from inside the vehicle; however if for example the vehicle is being driven at a high speed for a considerable amount of time, a speed sensor will detect that more air is needed to be added to the tire as this will prevent unnecessary tire damage. The speed sensor will then send the information to the electronic control unit which will then allow a valve to isolate that particular tire and allow inflation.
The main components of a CTIS are the electronic control unit which sends information to the drivers control unit on the dash board, which allows the driver to monitor the system. The electronic control unit also checks for tire pressure approximately every ten minutes, and then sends this information to the pneumatic control unit. The pneumatic control unit monitors and controls the air pressure and the wheel valves. This unit also sends tire pressure readings back to the electronic control unit. The wheel valves can be found on the exterior of each wheel. These valves isolate the particular wheel that need inflation or deflation, and allows air in or out of the tire using a tube that is run from an air compressor. A CTIS system works by taking the air from a compressor, which is normally the same compressor that is used for the brake system. A pressure switch is used to control the air for the brake system prior to using the air for the tires, which maintains the brake system as a priority.