Abstract: A rotary seal arrangement has a rotatable component (2) supported within a machine component (3), the machine component (3) forming a housing structure for a sealing means (23) which acts to seal off a high-pressure area (10) between the components (2,3) to allow the passage of high pressure fluid therebetween. The seal arrangement includes a holding element (30) for mounting in the machine component (3) to support spaced sealing members (23) therein to define said high pressure area (10) therebetween. The arrangement is particularly suitable for use where the rotatable component (2) is formed as a rotatable shaft and the holding element (30) and sealing members (23) are arranged around the shaft such as, for example, in a vehicle tyre pressure changing system for use on an agricultural tractor.