Rolex
Datejust 31 178313-0034— lug 16mm

The Rolex Datejust 31 reference 178313-0034 has a lug width of 16mm. This measurement is certified by Rolex and should be verified with a digital calliper before purchasing any aftermarket strap. Even a one-millimetre discrepancy will render the strap incompatible with the case lugs.

For the steel and yellow gold Datejust 31, the most suitable straps are alligator belly with a scaled grain for formal occasions, vegetable-tanned calfskin for daily wear with natural patina development, or shell cordovan for a compact texture and understated sheen. All options must feature curved ends to fit correctly within the 16mm lugs.

To replace the strap on the Datejust 31, use a spring bar tool — either lever or push-pin type — to release the spring bars from the lugs. A nylon-tipped tool is recommended to avoid scratching the case or gold lugs. The operation is fully reversible and does not require a watchmaker, but should be performed carefully.

Yes. Several artisan manufacturers, including Milano Straps, produce straps compatible with the 16mm curved-end profile of the Datejust 31. It is essential to specify the exact model when ordering to ensure the correct lug curvature. Straps listed on milanostraps.it are designed for this specific geometry.

The lifespan of a leather strap depends on the material and maintenance. A high-quality alligator strap, handled with care and stored properly, can last between three and six years. Vegetable-tanned calfskin offers a similar lifespan with the added benefit of developing a personal patina. Shell cordovan is the most durable of traditional leathers. Prolonged exposure to water, perspiration, and direct sunlight should be avoided.