i have bought a set of 997 turbo wheels off ebay and they looks very good i love them, but they didnt come with center caps, the man said the standard ones fit but i cant seem to get them to,

should all center caps be the same for porsche?

 

Wheels are not all the same, but if they are OEM you should not be having a problem with the OEM caps. Check the part number on the inside of the wheel to see what wheels you really have. If they have a Porsche part number it should be easy to find a set of caps. If they're aftermarket wheels, that will send you in the right direction for aftermarket caps.

 

IIRC, all OEM 997 wheels have a 60mm center cap so you shouldn't have any problems...but the TT wheels have polished caps so if you want your new caps to match the wheel make sure you get the right ones.

 

my wheels are not oem, they are 997 style to fit the 996 look exactly the same, do aftermarket wheels have diff center caps, if so do you no the size of them?

 

Different sized caps: yes--the wheel manufacturerers do that so you have to buy the caps from them.
The size of your caps: no idea...depends on the wheels. You can measure them and then start shopping. Check out what Ralph Boothe has...they're the bomb http://www.boothedesign.com/index.html