I've been using my OEM lug nuts for 5 years with my winter wheels (BSA 264). Now, the OEM lug nuts have both the flat seat and what appears to be a perfect conical seat for aftermarket wheels (see pic). It definitely looks like the conical seat has been engaging on all the wheels and all the lug nuts appear to be in good shape as do the wheels I never gave much thought to this til this year. Have I been doing this wrong for 5 years?

 

If the washers aren't binding in the lug holes you should be ok, but I would recommend getting a true tapered set (without washers) for your non-oem wheels.