How to wear Chelsea boots
Hem trousers to rest on the boot, or stack a little denim. Buy them snug through the gore, because elastic relaxes over time.
Trousers need to reach the vamp without concertinaing down to mid-foot. Suede pairs take denim, black calf takes chinos or a suit trouser. The gore should feel snug on day one, since elastic gives over a year or two.
With jeans
A straight or tapered leg. Heavy selvedge stacked over a slim Chelsea looks careless. Brown suede chelseas are the weekend pair.
With a suit
Black or dark brown calf, a leather sole or a fine rubber top-piece. Same rule as a loafer: this is an ankle shoe, not a motorcycle boot. Shop Chelsea boots rather than motorcycle boots when that is the job.
Common questions
Tuck or stack?
Neither extreme. A light stack on jeans, a clean break on trousers.
What socks?
Dark, matched to the trouser. White athletic socks fight the line.
For black tie?
No. That is a patent oxford or an opera pump.