For the rear:
Ordered Honda OEM from Bikebandit last month, still back ordered.
Needed to change tires, so I ordered a Motoz ultra heavy duty for the rear, arrived quickly( I forget which site). High quality but expensive (~65 USD). Currently installed and works fine.
Found some Pirellis on closeout at BikeBandit, ordered two as spares, arrived quickly.
For the front, a Tusk or IRC heavy duty, I forget which. Rim size is similar enough to my DRZ400S that I already had spares for that. Biggest issue seems to be that the rear is an odd size requiring a larger than common tube to seat the bead.