Maxxis do a 27.5 x 2.00/3.00 tube which will obviously fit a 2.8 tyre which is OEM for the rear mullet setup on my Frey Beast. It’s not a threaded schrader (like the AV19 schwalbes on my other bike) but the stem is 48mm which is ample length to grip with your fingers when locking on the schrader...