The Reason Some Semi-Trucks Have Spiked Wheels

So you know how intimidating it is to pass a giant trailer truck on the highway? Or maybe you have nerves of steel and it doesn't bother you to feel your little sedan get rocked around by buffets of air careening along either side of the giant, metal, death cylinder next to you. But what if the truck has gone full Mad Max and has spikes sticking out of its wheels? All we can say is: 1) Don't get too close, 2) Don't hang around in the truck's blind spots, and, 3) Don't go thinking you could win a spiked wheel competition with the beast of the road.

Alright, semi-truck wheel spikes aren't as crazy as all that. But they're a real thing, whether you've noticed or not. And to be fair, it's the wheel that's spiked — not the hubcap, not the tire (somehow), not the center cap, etc. Terms can get confusing here, especially because some sites refer to "spiked rims," even though it's not the rims that are spiked — it's the wheels. The rims are the outer, thin edges, while the wheel of a vehicle refers to all the non-rim parts of the non-tire parts. And spikes protrude directly from the lug nuts that connect the wheel to the axle. In other words, spikes are lug nut covers — that's it. They're like tribal tattoos: Unnecessary, but maybe more interesting than nothing. And since they cover the lug nut, they protect the thing that keeps the wheel and tire connected to the vehicle.

Knowing that wheel spikes are just lug nut covers definitely makes them less intimidating. You might wonder why lug nuts need a little spiked hat for protection, but semi-trucks drive around a lot more than the average car — it's kind of their thing. Over long, multi-thousand-mile trips, wheels and tires can take quite the beating, right down to the lug nut. And if it gets corroded from rain, snow, schmutz, or rock salt on the road? Well, that can be a bit dangerous. Hence the lug nut cover. 

Spiked wheels are protective in another way, too: Other drivers notice them. We joked earlier about how dangerous it feels to pass (or be passed by) a giant semi-truck on the highway, and of course their drivers know this, too. Very eye-catching spikes warn other drivers to give the truck some space and not hang around in its blind spots. This latter point is especially critical for trucks carrying long trailers, because the longer the trailer, the harder it is for the truck driver to see along its entire length. The rear of a trailer can also have a blind spot of up to 30 feet, and even the space in front of the cab can be blind for up to 20 feet. So yeah: Heed those spikes and don't assume the semi-truck driver knows precisely where you are and what you're doing. Highways are already dangerous enough as it is. 

But why cover lug nuts with spikes and not something else? Why not pink-rubber rabbit heads or sparkly black-light bulbs? Well, spikes or blades on wheels aren't exactly a new thing. In the 4th-century B.C.E. book "Cyropaedia," the Greek philosopher Xenophon wrote about chariots in warfare and drivers who "stand in wooden towers and the parts of their body ... defended by the towers are completely panoplied in breast-plates and helmets; and that scythes of steel have been fitted to the axles," per the University of Chicago. He attributes those words to the 6th-century B.C.E. Persian emperor Cyrus the Great. And while there's no telling if that account is true, it shows that the whole weaponized wheel idea has been kicking around for quite some time. Also, there's no record of ancient Romans using bladed chariots in combat. Sorry.

Finally, depending on your tastes: The spikes look cool. Maybe even cooler than a pink-rubber rabbit head. And while only between 10% and 15% of semi-trucks are owned by individuals and not companies, the drivers of owner-operated trucks can always customize their trucks to their heart's content. Some folks love individualizing personal possessions, from stickers on laptops to weird paint jobs for motorcycles. Provided a truck maintains legal width requirements for the entire vehicle and material specifications for the spikes, drivers can kit out their truck as they see fit. So why not spike things up? It might even be fun to see all those little sedans squirm at the sight of you.