Anyone know what the maximum size tyre will fit in?

i have the older rim braked version. (pre 2015 i think)

can fit a specialized 33c tyre in. no clearence for guards but rideable.

rim brake or disc version?

The rim brake version (well 4 year old version but still same I think) will take a ‘small 32mm’ without guards, or a ‘big 25mm’ with them, and everything in between is a case of it depends on exactly which tyre/rim and guards you have fitted. ie: you might get a 28mm under guards, you might not, it depends.

No idea about the Disc version though…

My rim brake 853 version from 2013 with guards will fit 28mm conti GP4000 front but only 25mm rear (sks chromoplastics). I reckon 32mm would be max without.

My 2017 rim brake version is quite happy with 28s and mudguards. There’s a bit of room to spare as well.

My disc version has 27s and SKS guards with a little room to spare.

2016 725 disc. 28mm Duranos and Chromoplastics. You’d get more without the guards. 30…33 maybe. I reckon any significant movement in the wheel could rub the fork after that. Big clearance for more on the rear.