Abstract: A tyre inflation system for an agricultural seeding machine is disclosed. The agricultural machine includes a jump arm supporting at least one press wheel. The tyre inflation system comprises an air delivery path arranged to be in air flow communication with a cavity of a tyre of a press wheel, and an air flow controller operable to cause a delivery of air through the air delivery path to adjust an inflation pressure of the tyre in situ during use of the agricultural machine. A planter assembly including a tyre inflation system and a tyre for use with the tyre inflation system are also disclosed.