Shows the tw (tyre width) for a 180/55ZR17 as 184mm. Last Bridgestone I used was a same size rear BT020 and the chain touched the side slightly and it rubbed on the hugger. That list on Bridgestone's website shows all the tyres to be a few mms wider except for one - 160/60ZR18 = 160mm.
The BT020 180/55ZR17 is shown as being 183mm wide.
BT016 170/60ZR17 = 173mm (3 mm less than the Pirelli 180 I am using). The outside diameter of the 170 is 7 mm taller than the 180 = quicker steering and slight change in engine revs at a given speed.