The 1.75" 507mm wheel worked out fine in the back. Its tight but it fits. The fork looks like it will only fit a 1" tire though. I'm going to try a mixed 520/507 set of wheels.
Edit: So for anybody running across this thread confused about the various 24" tire sizes, here is the break down:
24 x 1-3/8 (ISO 540) size not meant for BMX's, for small wheel roadbikes.
24 x 1-1/8 (ISO 520) junior cruiser BMX's built for this, also small roadbikes.
24 x 1-3/8 (ISO 520) similar but slightly wider than the 1-1/8 tires/rims.
24 x 1.5 (ISO 507) full size cruiser BMX frames for these diameter tires
24 x 1.75 (ISO 507) full size cruiser BMX frames for these diameter tires
24 x 1.85 (ISO 507) full size cruiser BMX frames for these diameter tires
24 x 2.XX (ISO 507) cruiser BMX's, dirt jump bikes, some small wheel MTB's
Last edited by riva; 05-13-11 at 12:27 PM.