I'm looking at a set of used wheels, and have been told that they are OEM. 18x7.5 50mm and 18x9 52mm turbo twists.

My understanding is that OEM wheels always have the offset and rim width stamped on either side of the valve stem hole. Is this true? Pictures in this case show no such stamping, so I'm guessing they are replicas?

Also, for you wheel fitment experts, I believe that these are a great fit for my 2003 996 C2, but can anyone confirm? Looking to pick these up for track wheels, so I'm not too picky about it being perfect to the millimeter, just want to be sure I'm not going to get rubbing.

 

I have a set of Turbo twists that I believe are OEM (fitted by the previous owner, but do have a Porsche part number on the inside that matches the Turbo Twists) and they do not have the offset stamped at the valve stem, it is stamped inside.

 

I wouldn't want a 9" rear for track use (or street use for that matter).
Those rears are probably Boxster fitment.

 

They are Boxster wheels, yes.

They fit the same size tires I'm running now, and with 1" narrower rears I'll be shedding some unsprung weight. I'm having excellent results with 265 rears, and expect even better with better tires and less weight. Until I've saved for my ultimate track wheel, these should be better than my current setup.

Assuming they fit my car without rubbing. =)

 

There will be no rubbing.
You will simply have an additional inch of clearance on the inside.