Hi there Kev,

that's a bit far off from wiring (as the title suggested) - you can probably squeeze in a 140/80-18. A 130 will definitely work. After having tried out a lot of different tyre sizes (i.e. hand-me-downs from friends), I settled on 120/80-18 or 4.00-18 for the rear tyre.

Cheers,
Greg

The problem up to a 140 isn't so much the rim size, but the fact that it'll rub on the chain tubes. With an open chain and a 2.5" rim and you can surely go wider. (But why would you?)

Cheers,
Greg