[mqlkib]

Don't forget about π, with it you get 18.3 wheels. No problem with really fat tires, I think.

[r_c_a_d]

When I read this I thought, what is n? You mean pi, right?

Yes, 18.3 inch wheel is what I got. Here in the UK, the "wheel" size includes the tire as well, I think.

I guess if the rim is 17 inch diameter then 18.3 is only a tire width of 0.65, which isn't very fat.