Why Do Semi Trucks Have Spikes On Their Wheels?

For many drivers, cruising alongside an 18-wheeler can be a little nerve-racking—a feeling that's compounded when you realize some of the truck's wheels are covered in metal spikes. Though the ornaments may look a bit menacing, they’re not there to scare you.

As Big Rig Pros explains, the spikes’ main purpose is to cover a wheel’s lug nuts (which help fasten tires to their axles). Considering the countless miles that 18-wheelers traverse, it’s no surprise that their lug nuts suffer more wear and tear than those of other vehicles. The spikes shield lug nuts from dirt and keep them dry from precipitation, forestalling rust and preventing them from loosening.

While the covers are sturdy enough to do that job well, they aren’t always as indestructible as they appear. Many are manufactured from plastic made to look like chrome. As for why so many truck drivers opt for pointed covers over flat ones, it may be more of a style choice than anything else. When you’re spending dozens of hours a week in your truck, you might be inclined to trick it out a little. As Big Rig Pros notes, it’s not unlike an office employee decorating their cubicle.

More Articles About Trucks:

If the flashy spikes catch your eye on the road and remind you to keep some distance between your car and an 18-wheeler, that’s not a bad thing. Truck drivers have significant blind spots directly along the sides (and front and back) of their trucks, and accidents are more likely to happen when an approaching vehicle strays into one of these so-called “no-zones.” In this way, the spikes may not just be protecting the lug nuts—but also you, the truck driver, and everyone else on the road.

And if you need gift ideas for truck drivers, be sure to check out our gift guide.

Have you got a Big Question you'd like us to answer? If so, let us know by emailing us at bigquestions@mentalfloss.com.

A version of this article was originally published in 2021 and has been updated in 2022.