i hope i can describe this properly...would you please measure the distance between 2 spokes at its widest, right where the radiating spokes end at the outer rim?
or another way - the empty spaces between the radiating fins basically look like triangles. the pointed edge is where the radiating spokes converge on the center hub of the wheel, and the widest part of the triangle is where 2 fins end by the outer edge...
thanks!