There is really only one offset now, the white wheel which fits all current cars except maybe Edam, not sure if they have changed yet or not. It is what is generally called the Mugen/Kyosho wheel but will fit all the others out there now too. There are some slight differences in the offset of Mugen/Kyosho/OS2 wheels from one brand to the other but only 1mm or so, they all should fit fine. The yellow wheel is the old Serpent OS1.
Sean. Certified speed crazed mowron.
Team Shepherd USA