Do you see anything on the inside of the wheel that looks like a Porsche part number (e.g. 928.xxx.xxx.xxx, 993.xxx...)?

If not then they are aftermarket. Those don’t look like the inside of Porsche OE wheels to me.

 

I did not see any Porsche part numbers on the inside, nothing that started with a 9XX. More than likely I will have to take a measurement on the ID of the cap cutout and lathe or CNC the ODs down to fit. It wont be till next year when I get back to work. I will post the results. Thank you Stan, Tony and Dave for replying to my post and helping with my issue.

 

Who knew that new center caps could be such a pain?!

If I might make a suggestion, perhaps since they are new they might require a bit more pressure to install the initial time or two. Give them a strong whack with the palm of your hand or a gentle tap with a rubber mallet, that might be all that is needed. Some lubricant might also be helpful.

 

I have had this problem before with aftermarket wheels and have had to make mods to center caps.

 

So I used my calipers to measure the ID of the wheel center opening and found them to be 3.010" or 76.45 mm. then measured the center cap which measured to be 3.040" or 77.21 mm. Does anyone know the standard size of the Porsche center caps? My understanding is that they are the same except for the Macan, which I think are smaller.

 

That is such a tiny difference. One is intentionally slightly larger than the other, it’s what keeps it on the wheel. Search Rennlist and you will find others that have trouble because their caps spin and produce noise or they won’t stay on.

You could try the other three caps on that one wheel first to see what happens, but it would seem that you need to apply more force to press the cap(s) in to place.

Alternatively, take the whole lot to a tire shop and have one of their experienced techs pop the caps on for you.

 

I just measured a couple of center caps out of 928 Manhole covers. The caps measure at just under 3" (2.990 & 2.885).

The holes in the wheels measure at right around 3" (2.998 & 3.010).

I also have a 944 Phone Dial. The hole measures just over 3" (3.020). I don't have a center cap for that one.

Hope this is of use.

 

Thanks guys, I tried to use a rubber mallet on it but was in fear of it breaking. I will check the other caps on the one in question but had the same problem with the other front also. Maybe they do need more force, just don't want to damage the new caps.
Thank you Joe, your wheel holes seem to measure similar to mine. Did you have to drive your caps in? Are your PN's for the caps the same as mine (993 361 303 00FFF)?

 

No. The caps have a 'springy' sheetmetal piece riveted to the back, that goes into the 'inner' part of the hole in the wheel and holds it in place.

When the caps are in place, there's a small gap all the way around. Maybe big enough to slide a piece of paper in.

No part number on it that I can see.

These are the anodized center caps for the Manhole Cover wheels that came on the car.

 

Thank you Joe for your time and help.

 

Geo,
I assume your center caps fit the rear wheels perfectly? My own experiences have been that the center caps of this style fit across many styles of OEM wheels such as the 996 C4S Twisties, the Carrera Lightweight wheels and the 17 incher Cup I wheels. I have a feeling that, in your situation, you front and rear wheels have different sized holes.
Steve

 

Just pulled the caps off my Cup Is and part numbers are below. Interestingly, the front are less concave and have JST stamped below part number. The rears have JOR stamped below part numbers and also have an additional tab.

Rear center cap

Front center cap

Of course I have no idea if the fronts are actually front and rears are actually rears or if they are just different caps purchased at different times by previous owners.

 

Maybe you can try sanding the paint of the wheel and then they'll fit.

 

Modify the center caps to fit, not the wheels.

 

The answer is in your sig.
Just make sure the point of the shield is pointing to the valve stem. That's what really matters.