Green’s Dictionary of Slang

(Aus.) elastic-sided boots.

1894–5		H. Lawson ‘Going Blind’ in Roderick (1972) 175: Crimean shirts, strapped trousers, and elastic-sided boots — ‘larstins’, they called them.
1901		H. Lawson ‘“Buckolt’s Gate”’ in Roderick (1972) 440: Chaps in tight ‘larstins’ (elastic-side boots) [...] went round the room with their eyes — most of them — cocked at the rafters in semi-idiotic ecstasy.