The legal tread depth limit for motorcycles, mopeds and scootersover 50cc in the UK is 1mm across three quarters of the width of the treadpattern, and with visible tread still remaining on the other quarter.
Crossply (or bias) tyres have a relatively simplestructure with sturdy sidewalls and are particularly suited to off-road use asthey resist impact well.
In this photo we have a 180/55 ZR17 (73W) tyre, whichmeans it’s 180mm wide, and the profile height is 55% of that, so 99mm.
The design of a decent motorcycle tyre is all about itsconstruction, compound and tread pattern.
Simply put, a single layer of material on the inside of thetyre’s carcass.
Eventually tires wear out, and needreplaced. Typically the rear tires start to square up, losing their roundedprofile, as the center of the tread wears away faster than the shoulders.