Ok, I finally got around to measuring my 07 KX250F Rear wheel.
Stamped: PFD - 0025 -
AXLE OD: 25MM -
Outside of BRG TO outside of BRG 133MM -
ROTOR OD 240MM -
ROTOR BOLT CIRCLE 4 ON 133MM -
SPROCKET BOLT CIRCLE 6 ON 150MM
FITS 07-08 KX250F KX450F Possibly others.
2000 K5
Stamped R-1237 -
AXLE OD 20MM -
Outside of BRG TO outside of BRG 130MM -
ROTOR OD 220MM -
ROTOR BOLT CIRCLE 6 ON 116MM -
SPROCKET BOLT CIRCLE 6 ON 150MM -
FITS 97-98 KX125 & 250, 97-04 KX500, in fact it fit's all the way back to 1989 but the hubs are a different casting.
So, the wheels will swap, the sprockets will interchange, BUT the rotors will not interchange.