29x2.4 ardent, on a dually rim is 64mm wide, accross the carcass, knobbles are slightly less wide at 61.5mm
It does fit in the back of my large el mariachi with approx 4mm room on the chainstays to the knobbles ( chainstays are narrower at the knobbles).
Dia, approx 753mm
2.4 ardent on an arch ex is 59mm carcass, 61 mm knobbles. Obviously it fits in the el mariachi
Dia approx 749mm
Both fit in my kona raijin too, but with a scant 1.5mm clearance on the dually. It improves slightly at max chainstay adjustment. But not loads.
For reference, a knard on a dually is 75mm wide but also tall.
Dia approx 766.
I'm not sure I have a point but, I measured so thought I'd share

*edit, nearly forgot. A knard on a dually does not fit a 2012 reba, a 2013 sid, or an on one monocoque fork