Rear wheel size

[Paull]

My CB550 f2 has a 16ins wheel with a 120/90 tyre on it, what differents will this make over the standard 18ins wheel, the bike is now far from standard.
Paul

[Bryanj]

Except for the fact it won't fit in a standard mudguard not a lot

[K2-K6]

I work it out like this to get overall diameter of wheel/tyre; (thinks it's correct but please add if not)

Tyre width is 120mm and distance from rim to tread is 90% of this hence the marking 120/90.

So you can go 16 inches in mm then add 2x the above calculation to get overall diameter of assembly.

Do the same for the original spec to compare.