Central tyre inflation system and method

A central tire inflation system (CTIS) for a vehicle includes a reservoir for supplying air to the vehicle tires, a pressure sensor for monitoring air pressure in the reservoir, a compressor for supplying compressed air along a first flow path to the reservoir, a compressor timer for monitoring the run-time of the compressor, a dryer disposed on the first flow path for drying air supplied by the compressor, a purging system for routing air through the dryer along a second flow path to purge liquid from the dryer, and a controller for controlling the flow of air in the CTIS. The controller is configured: to activate the compressor in response to a request for a compressor operation, after which operation the air in the reservoir is at a post-operation pressure; when the compressor operation is complete, to determine a compressor activation period, and to determine if the compressor activation period is greater than or equal to a target period; and if the compressor activation period is less than the target period, to keep the compressor activated until pressure in the reservoir increases to a base target pressure greater than the post-operation pressure; and if the compressor activation period is greater than or equal to the target period, to keep the compressor activated until pressure in the reservoir increases to an elevated target pressure higher than the base target pressure and to activate the purging system to route air from the reservoir to purge the dryer of liquid.