I think shiggy's chart must have an anomaly, or either the method for measuring is different to how the RoRo look. Usually tyres are measured on the width of the widest tread point....and due to the fact that RoRo's have wide knobs on a thin carcass the volume of the casing is much smaller. Looking at a 2.25 they will look slightly bigger than a 2.1 RR, but nowhere near the size of the 2.25 RR.
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