IATE geeft 'gewelfde tong' als de vertaling voor de Franse term 'cuir pour (languette à) soufflet'.

Term leder voor de gewelfde tong
Betrouwbaarheid 2 (Minimale betrouwbaarheid)
Termreferentie Secr.Fed.v.Ned.Schoenfabr.
Opmerking bij term tong die met het voorblad uit één stuk leer is gesneden

of '(vast)genaaide' tong

Cf.:

(NB: stitched, stitching, festgenäht, stitched-in, sewn)

“So, what is a gusseted tongue? It is the tongue of your hiking boot that is attached, at the sides, to the rest of your hiking boot. When you look at the boot from the front, without any laces in it, you should see the tongue area very prominently. Now, open up the tongue and look at the side of it. Is it either tightly stitched to the side or is it just a folded and continuous piece of leather that extends to the rest of the uppers? If so, it is a gusseted tongue.
Now, the important part here is whether or not it is a "full-gusseted" tongue or a "half-gusseted" tongue. Here's how you tell.
If the boot is a full length boot, meaning that it has a lower part and an ankle support area that extends up the ankle a bit, a full gusseted tongue will extend all the way up to the top of the ankle support. If it is a half-gusseted boot, the stitching or the attached area will stop before it goes up into the ankle support area (scree collar).”
[...]
“A full gusseted tongue is also called a Bellow's tongue in some circles.”
(http://www.streetarticles.com/recreation-and-sports/if-youre...

“Specificaties Timberland Summitscape FTP Heren Donkerbruin
[...]
Volledig vastgenaaide tong zorgt voor comfort en voorkomt het binnendringen van steentjes”
(http://www.futurumshop.nl/timberland-summitscape-ftp-wandels...

Kunststofftechnisches Wörterbuch”:
“tongue gusset (shoe = bellows tongue)
Lasche f
attached to the uppers (rundherum am Oberleder festgenäht) as opposed to tongue, which is fastened only in front”
(http://books.google.nl/books?id=r6sLoNFuTXMC&pg=PA505&lpg=PA...

“BELLOW TONGUE
A stitched-in tongue, giving protection from the elements and the ingress of debris.”
(http://canadadawgs.com/BELLOW-TONGUE.html)

“Bellows tongue - Languette à soufflet“
(http://www.btb.termiumplus.gc.ca/tpv2alpha/alpha-eng.html?la...

“A gusset is a thin piece of flexible leather sewn to both the tongue and the upper. It keeps out water and stones. A "bellows" tongue has wide gussets, allowing it to open further so it is easy to put on.“
(http://www.gorp.com/parks-guide/travel-ta-hiking-boots-los-p...


Vgl. tevens:

XA PRO 3D ULTRA 2 GTX® W
« Languette à soufflet
La languette est reliée à la tige pour empêcher les corps étrangers d’entrer dans la chaussure. »
(http://www.salomon.com/be/product/xa-pro-3d-ultra-2-gtx-w.ht...

“Specificaties Salomon XA Pro 3D Ultra 2 GTX Heren Hardloopschoenen Grijs
[...]
Ingenaaide tong voorkomt het binnendringen van steentjes”
(http://www.futurumshop.nl/salomon-xa-pro-3d-ultra-gtx-heren-...


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Note added at 1 dag10 uren (2013-10-09 22:06:01 GMT)
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Correctie:

De voorgestelde vertaling luidt niet (doorlopend) ingenaaide tong,
maar (volledig) ingenaaide tong.

ik vind hier ook vaak balgtong (in het Engels bellows tongue) voor, inderdaad een tong die volledig ingenaaid is, met een plooi om te verkomen dat vuil/nat in de schoen komt