Just fitted a Mitas CO2 rear tyre today, man that digs in and goes!!120/100/18 ,running a 14 tooth front sprocket the tyre JUST misses the black mudguard near shock by about 5mm!!
I'd think a larger than 5mm gap would be better - do you not have probs with mud not clearing the treads and blocking the gap between the tyre and swingarm/mudguard?