This is a similar Knard tread we previously introduced on a 29 x 3" casing, made up of low, closely spaced knobs, an effective tread for going fast over varied terrain.
We chose 41mm because it's meaty enough to conform to the ground surface, absorb irregularities and provide a decent sized contact patch.
The 27, 60 and 120tpi casings do a good job and feel lively, though the 120tpi is lighter, more supple, and features a folding bead.