I measured some 26" BAs and they measure approximately 1 7/8" wide x 1 7/8" high from rim. Even so looking closely at the Donlop on the front fork, a true 1.75" it barely fits. It would be very tight to go any wider. Height is no problem. The front fork has tighter restriction on my bike, I think. To get true clearences I would need to take off the wheels.
If I want kevlar protection this leaves me with Marathons or Continentals Contacts.