In late 1972 Seiko introduced its third original dive strap design the XGL-731. This strap has the nickname of “Tire Tread” and was only supplied on a single model of watch.
|JDM Release||1972 - 1977|
|Supplied JDM Models||6105-8110|
The XGL-731 was supplied on the 6105-8110 that initially had the model number of 61MC 022, this model number changed to YAH028 in 1975 until the end of the models life. When first released in late 1970 the 6105-8110 was provided on the second dive strap released by Seiko, this strap does not have a known model number but is commonly known as the “Chocolate Bar”. The 6105-8110 (55027) for international markets only provided on ZLM01 for duration of product life.
The XGL-731 was the last of the Seiko dive strap designs released before the introduction of the XGL-801 that was the revolutionary design that was supplied with the 6159-7010 tuna that included vents allowing the strap to change size with compression caused by an increase in water pressure.
In the JDM Seiko catalogs the XGL-731 can be seen pictured here.
The strap has the following specifications.
|Length - Tail Section||131|
|Length - Buckle Section||80|
|Strap Width - Round Tail End||19|
|Strap Width - Buckle End||19|
|Buckle Width (maximum)||26|
The "tire tread" marking is 2.8mm wide and surrounds an organic styled pattern, on the outer edges there is a similar but finer pattern. The strap has two independent keepers that have a diamond pattern on the top surface. The inside of the buckle is simply stamped with SEIKO. On the inside of the tail end there is a Seiko logo on the top edge and Japan centered below this. The small pip moulding mark found on the rear side tip of the ZLM01 strap is not present on the XGL-731. On the buckle half of the strap the model number XGL 731 is embossed on the inside of the spring bar end. The strap takes the 2.5mm fat spring bars that are common on Seiko divers.
There is also an orange version of this strap, bu I do not believe that it was ever supplied with a watch, instead it was available as an aftermarket accessory. The first official documentation I have seen confirming the existence of the orange variant of the XGL-731 strap was in the Seiko 1972 No.1 Watchband Catalog. You will note that the catalog states the reference as D-2 (presumably Dive 2), then (Diver), and the price of ¥1,000. On the lower section of the page it lists the two color options Black and Orange as well as the size (19mm).
These straps are not commonly found these days and when they do come up for sale are usually priced around $400-500. Luckily for people wanting to get an authentic look for their 6105-8110 there are a couple of alternatives available.
The first reproduction of this strap was released a number of years ago from WJean (www.strapboutique.com)
The newest option for this style strap is from Uncle Seiko (www.uncleseiko.com). In addition to the original 19mm width, there are also 20mm and 22mm sized versions available for customers who wish to pair this original design with other watches.
Thankfully neither the WJean or Uncle Seiko straps have the Seiko branding on them so it is easy to identify an original strap.
The XGL-731 has a distinctive design that matches well with divers from that period. It is the logical match on a Seiko 6105-8110 from late 1972 onwards, for collectors who are looking to keep the original configuration.