Green’s Dictionary of Slang

1. in pl., high or Wellington boots.

1835		G. Kent Modern Flash Dict. 25: Pickling tubs – Wellington or top boots.
1840		Flash Mirror 18: Trotter cases, mud pipes and boot kivers, carved to fit any pins [...] N.B. — Old pickling tubs and crab shells made and mended.
1848		Flash Dict. in Sinks of London Laid Open [as cit. 1835].
1859		Matsell Vocabulum.

2. see powdering tub n.