When is a tyre considered worn?
The stock 29er tyres are still on my Cube. (Tough Tom/Rapid Rob) The front tyre looks like new but the centre knobbles on the rear tyre are well down, maybe 1 - 1.5mm remaining. A new tyre has tread depth of around 5mm. I have a new tyre waiting to go on but wanted to get the most out of the current tyre. So my question, when are they considered worn, is it when the knobbles on the centre are completely worn away but the outer knobbles are still intact and near enough full depth or is it like mine at the moment and only a mm or two remaining?