What Are Those Spikes On Semi-Truck Wheels For?

Top Gear fans might recall Jeremy Clarkson once fitting “Boudica spikes” to a Fiat Coupe as part of a unique challenge. The purpose here was to provide the little Fiat with some destructive power, but is that really what semi-truck drivers are looking to achieve with the long, protruding spikes on their wheels?

Fear not, as that isn’t the case — far from it, actually. The spikes often spotted sticking out from truck wheels are simply decorative lug nut covers, designed to protect the nuts beneath from getting covered in road debris. This prevents the nuts from getting rusty, which in turn makes removing the wheels easier during routine service, such as brake overhauls. It may seem unnecessary for them to sport such a menacing shape, but in reality, the spike is actually quite effective. Their smooth, pointed profile means dirt and debris from the road have very little chance of clinging to the spike, and it also means that stones can bounce off of them easily, rather than hitting and potentially damaging the wheel or lug nuts instead.

There is another reason why semi-truck drivers love spiked lug nut covers, and it has nothing to do with keeping their wheels clean and protected. Rather, the spikes can act as a safety warning to other drivers, deterring them from getting too close. Naturally, the largest semi-trucks on the road have some pretty significant blind spots, and the last thing a driver wants when piloting an 80,000-pound truck on the freeway at speed is having cars sit close, potentially in those blind spots.

The thought here is that drivers will notice the protruding spikes and decide to keep their distance, thus giving truck drivers a little bit of breathing room on the road. Giving big rigs space while driving is a win-win for everyone, so it’s important to know how to drive safely beside semi-trucks and keep out of their blind spots when possible. These spikes may help with that.

But don’t worry about these spikes posing any danger to you, though, as they’re unlikely to carve gashes into your door or burst your tire’s sidewall with a passing glance. This is because they’re typically made of either aluminum or plastic, and therefore are more likely to shatter if they were to contact another vehicle on the road.