The Cartier Tank Must WSTA0085 is the black-dial Tank at its most accessible: black lacquered dial, steel case, quartz movement, black calfskin strap. It's the version of the coolest modern Must that most people actually buy — and it happens to be the single best Tank in the lineup for strap changes, for a reason that becomes obvious the moment you see a color against that dial.
Correct size first, then the part that makes this reference fun.
Cartier Tank Must WSTA0085 Strap Size and Fit
The essentials:
- Reference: WSTA0085, Tank Must, Large model, black lacquered dial
- Case dimensions: 33.7 × 25.5 mm, just 6.6 mm thin
- Correct strap size: 19 mm
On the product page, select the 19 mm option. The watch uses standard spring bars and a steel ardillon buckle — any strap change takes a minute with a basic tool.
The buckle-end trap: the factory strap narrows toward the buckle, and that smaller number (around 16 mm) occasionally shows up in spec sheets. The lug width — the number you order — is 19 mm.
The black-dial family, sorted: Cartier makes the black-dial Tank Must Large in two configurations — this calfskin version (WSTA0085) and an alligator version sold under WSTA0072 and, on newer paperwork, WSTA0108. All of them are the same 33.7 × 25.5 mm case, so every black-dial Large takes 19 mm — as do the silvered Larges. Only the size changes the strap: the Small takes 16 mm and the XL automatic takes 23 mm.
The Tank That Went Dark
The Tank has been Cartier's rectangle since 1917, but the black lacquered dial is pure Must attitude — a nod to the 1970s Must de Cartier era, when the brand broke its own rules with lacquer dials and colored straps. On the WSTA0085 the dial is deep gloss black with rhodiumized silver-tone sword hands gliding over it, framed by the steel case and the beaded crown with its blue synthetic spinel. Quartz inside, 30 meters of water resistance, 6.6 mm thin: a watch that disappears under a cuff and gets noticed the moment it comes out.
A Black Dial Is a Dark Room
Here's what makes this reference different from every silvered Tank: color behaves differently against black. On a silver dial, a colored strap gently tints the whole watch. Against black lacquer, color glows — the dial gives it nothing to compete with, so a red or green strap reads twice as saturated as it does on any other Tank. Cartier understood this in 1977 when the original Musts paired dark lacquer with bold straps.
In other words, the WSTA0085 is the Tank that rewards courage. These are the most popular strap choices among black-dial Tank owners:
1. Red Leather – The 1977 Pairing, Reborn
Black lacquer and red leather is the original Must combination, and it remains the most dramatic thing you can do to a Tank. Against this dial, a red leather strap for the Cartier Tank doesn't read as a novelty — it reads as intent, the black dial making the red look deeper and more deliberate than it ever could on silver. If you bought the black Tank to stand apart, this is the strap that finishes the thought.
2. Black Leather – The Monochrome, Maintained
The factory calfskin is the strap that will wear first — it's on duty every day, and calfskin creases and grays with use. A black leather strap restores the all-black look Cartier shipped: the stealth Tank, dressed for everything. Buy it before the factory strap fades and rotate the two; each lasts far longer with rest days.
3. Green Leather – The Modern Statement
Green and black is the pairing of the moment in watches, and it's tailor-made for this dial: deep green against gloss black reads rich rather than loud. A green leather strap turns the WSTA0085 into the Tank people ask about — contemporary, confident, and still perfectly wearable with anything.
4. Blue Leather – The Quiet Color
If red and green are further than you want to go, navy is the subtle route: a blue leather strap adds depth to the black dial without announcing itself — the color only reveals itself up close, which suits the Tank's whole character. The refined middle ground between monochrome and statement.
Every color above — plus brown, white and more — is in the full Cartier Tank strap collection, all in 19 mm. (One note for this size: crocodile straps for the Tank run only up to 17 mm, so the 19 mm Large stays with smooth leather — which suits a 6.6 mm case best anyway.)
Keep It Slim
At 6.6 mm, the Tank Must all but vanishes under a cuff, and slim, flat straps keep it that way. Padded straps lift the case and break the line — every strap linked here is cut flat, in the proportion the Tank was designed around.
Final Thoughts
The WSTA0085 has no bracelet and no complications — the strap is its entire wardrobe, and the black dial makes every choice count double. Helvetus is one of the leading names in the aftermarket strap world, and our Tank straps are cut precisely for the 19 mm large case, buckle included. Rubber straps across our range carry a lifetime warranty, shipping is free worldwide with no import costs, and more than 50,000 watch owners already trust us with their straps.
Cartier gave this Tank the dark room. You choose what glows in it.
