Here is the short story.
You can use:
89-02 KX125, KX250.
89-04 KX500.
89-94 KDX200.
Rim widths will be either 1.85 for the 125's or 2.15 for the bigger bikes.
Rim diameters will be either 18" or 19" depending on the year and model.
Long story:
Here is the hub info I have and what year's the book says they are for:
R-1213 ? GRAY ? 20MM AXLE - BRG TO BRG 130MM - ROTOR OD 220MM - ROTOR BC 6X ON 116MM ? 36 SPOKES ? book says it FITS 89 KDX200, KX125, KX250, KX500
R-1213 - GRAY - 20MM AXLE - BRG TO BRG 130MM - ROTOR OD 220MM ? ROTOR BC 6X ON 116MM ? 36 SPOKES - book says it FITS 90-94 KDX200, 90-96 KX125 KX250 KX500
R-1237 - GRAY - 20MM AXLE - BRG TO BRG 130MM - ROTOR OD 220MM - ROTOR BC 6X ON 116MM - SPROCKET BC 6X ON 150MM - book says it FITS 97-98 KX125 & 250, 97-04 KX500
R-1287 - GRAY - 20MM AXLE - BRG TO BRG 130MM - ROTOR OD 220MM - ROTOR BC 6X ON 116MM - SPROCKET BC 6X ON 150MM - book says it FITS 99-02 KX125, 250