As standard on most recumbents
... the front wheels are 406mm/20" (tadpole style) and most noteworthy it has the 599mm/26" rear wheel.
Due to it's already familiar frame like the GT20, accessories such as chain gobblers, head rests, accessory posts, grab handles and mirrors will fit the newcomer.
I particularly like the higher chain and derailleur ground clearance provided by the larger diameter wheel.
The ride is noticeably smoother than it's shorter counterpart the GT20 with 20" (406mm approx.) wheels all round.
GT26 - GT700
...but don't quote me.