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Wheel nut bearing surface.

A mechanic kept saying that tapered nuts were good for wheel nuts in endurance for 12 hours. There are normal nut types and bolt types for wheel nuts, but here I would like to write what I think about the seat surface, that is, the connection surface with the wheel.

There are roughly three types of seating surfaces. Tapered type with a mortar-shaped tip that narrows linearly. Spherical seat type that is literally spherical. The ground contact surface is a flat seat type.

Considering the strength, the taper type with a tapered tip has many contact surfaces, and I feel that it is somehow good. Probably, the mechanism mentioned above also emphasized from the image.

However, Porsche, the mass of rationalism, is all spherical except for the center lock. The reason is quite simple. The taper type gets in as you tighten it, and you can't remove it when heat is applied.

In contrast, the spherical surface can have a large ground contact surface, and the entire spherical body ensures uniform tension, and at the same time, the spherical surface becomes a stopper and does not enter. This is the reason why the world's racing cars use spherical surfaces.

By the way, in the case of Porsche, it is an aluminum alloy that is used in general vehicles. This ensures strength and lightness comparable to aluminum wheels. The material used for racing cars other than the center lock, commonly called cup nuts, is steel. This is to increase the strength in consideration of the increased number of wheel attachments and detachments compared to ordinary cars.

Also, there is a trend to appreciate the titanium material, but my job is skeptical. Because there is no thermal expansion, or the expansion rate is extremely small. This makes me worried about whether the bolt tension can be used.