I just measured the current tyres I have on, if anyone cares.
Minion DHF 2.5 WT = 62mm* (2.44″)
High Roller 2 2.4 = 61mm (2.4″)
Minion DHR2 2.3 = 57mm (2.24″)
Minion SS 2.3 = 57mm
* The DHF is brand new, unridden. The rest have had months of use.
On 27.5 Flow EX (25.5mm internal) rims, measured to the outside of the side knobs.
All the Maxxis Exo tyres I’ve had have got a bit bigger over their first few rides as the carcass stretches, so I expect the DHF to grow a bit.
The Shorty 2.5 WT and 2.3 I had on over the winter were similarly sized – slightly smaller casings but more sticky out side knobs so they measured the same.