These come mounted on the new 690's... that should tell you something. I tried many combinations and brands on my 08 690E and the MT21's are hands down the best for DS. I have ridden the CDR and COBDR with these tires and would have no other. Plenty of miles left in a set after either of these treks. Some brands make the front end squirrely at high speed, but not the MT21. They are quite good on the road at any reasonable lean angle.
While these tires handle awesome in dry and wet road conditions they make my 690 Enduro look castrated.
I haven't tried them in any type of dirt conditions, but that's not why I bought them. I needed safe tires for my daily commute to work and these tires delivered the confidence.
I've had them for a few weeks, with around 600 miles on them. The rear is just starting to show signs of slight wear, nothing out of the norm.
It is a good tire with a UHD tube, but it feels much better with the TUBliss insert. The full circumference support of the sidewall helps eliminate the tire roll through hard turns. Also, being able to run the tire at 10 psi (or less) really lets it soak up small objects in the trail.
Great off road. I use 70/30 off/on road use. Tread life seems ok at 3k. For the 30 percent of on road riding I do it works but stability is soft/floating during braking on pavement. Star rating is for on road use.
Great traction off road. Pavement use kills life of tire. I mostly use off road but the on road use I have ridden wore out the tire. 70/30 off/on road at 3k miles and I'm looking for another rear tire already.