This time, I’m diving into a rather niche topic: the correct way to install wheels on our air-cooled Porsche 911 (964 model).
For those who have owned air-cooled Porsches for years, this might seem like “Oh, it’s just that simple,” but this article also reveals Porsche’s deep dedication to driving performance, so I’d like to share it with you.

Genuine Porsche Wheel Nuts and Theft-Prevention Nuts

The genuine Porsche nuts used on models like the 964 (Part No.: 99918200336) are made of aluminum and are incredibly light.
Their weight is an astonishingly light approximately 18 grams. When you hold one in your hand, it’s surprisingly light for a solid metal nut—you might even wonder if it’s made from reinforced plastic or something similar.

Weighing just about 18 grams

On the other hand, there’s another type of nut: the genuine theft-prevention (lock-up) nut (Part No.: 92836104703).
This nut is designed so that you cannot turn the bolt without a special key. It consists of three parts: the bolt itself, a cover with a keyhole, and a cap. Despite its size, it’s also quite light, weighing only about 49 grams.

Since the 964 has 5-lug wheels, it uses four regular nuts and one theft-prevention nut, totaling five nuts. However, having just one theft-prevention bolt can look a bit odd.
So, I considered not using the theft-prevention bolt and instead buying four regular bolts to replace them. But even though the bolts are lightweight and located inside the tire, I wondered if the 31-gram difference might affect the wheel balance. That’s why I decided to investigate this matter.

The theft-prevention bolt is large and protrudes, making it somewhat noticeable.

Porsche Specifies Where to Use the Heavier Theft-Prevention Bolts

Reading the 964 owner’s manual reveals the following instruction:

When mounting the wheels, ensure that the wheel bolt identified by paint is positioned farthest from the valve. Always install the lock-up wheel nut on the wheel bolt identified by paint.

What does “wheel bolt identified by paint” mean? When I checked my 964, I found a bolt painted in a fluorescent color. The manual instructs that the air valve should be positioned farthest from this painted bolt, and the theft-prevention bolt must be installed on this painted bolt.

In other words, it looks like the diagram below:

Only one bolt is painted

Porsche strictly specifies this to minimize the impact of bolt weight differences on wheel balance.

If You’re Concerned About Wheel Balance on Your Air-Cooled Porsche, Check This

Our 964 was originally installed correctly, and the wheel balance was carefully adjusted, so there’s no particular issue. However, if you’re worried about wheel balance, it’s a good idea to check whether the bolts are installed exactly as specified.

If your tires are mounted and dismounted at a Porsche dealer or specialist shop, there’s likely no problem. But if you use a general tire shop, it’s possible they might not follow this specification.

By the way, I tried switching to all regular bolts instead of theft-prevention bolts and vice versa, and here are my impressions:

• The front wheels felt smoother with only regular bolts, without theft-prevention bolts.
• The rear wheels felt smoother when using theft-prevention bolts.

That said, since my wheels were very precisely balanced, I didn’t notice a dramatic difference, but the subtle changes in rolling smoothness were interesting.

Why not take this opportunity to double-check the wheel bolt positions on your beloved Porsche?