ANy reason why i cant use my standard locking lug nut on aftermarket wheels? The guys who put my wheels ontoday said it would work and that i should go to Autozone or Pep Boys and get some new ones.

Why is this? And what size do i need?

 

Don't see why not.
The lock has a cone shaped head that fits the wheel properly?
Length of exposed thread is sufficient?

 

The openings on some aftermarket wheels are smaller than the OEM opening so what fit your OEM wheel won't fit some aftermarket wheels. My Volks use 19mm nuts whereas the OEM were 21mm. You can't get the OEM lug wrench in the opening of the Volks if you wanted to use a 21mm nut.

 

dont forget about the contact, some lug nuts have conical, rounded, or flat tapers. Depending on the wheel you need to match it as well.