Let's offroad / mountain bike / mtb / ride dirt

Ahh, realised my mistake there. Twas a simple math error on my behalf. Coming out at 64.2 now for the 2.35 tyres and 66 for the 2.55s. Though they're probably not that accurate either as tyre manufacturers have a tendancy to be a pretty inaccurate with their measurements at times.

I think it's probably going to be a little below those numbers, as you're going to be running slightly lower pressures which will mean less tyre height at the ground and therefore lower GIs. Might be wrong though.