The small, spiky hairs you see on motorcycle tires are actually a by-product of how tires are made. These little spikes, known as “vent spews,” don’t have any impact on how the tire works.
While “vent spews” might sound like an odd name, it’s just one of the many terms used for these tiny fibers. Other names include sprue nubs, tire nibs, gate markings, and nippers.
But why do these hairs exist in the first place? To answer that, you need to understand a bit about how tires are made.
Tires start off as what’s called a “green tire.” This is just a tire-shaped rubber compound that hasn’t yet been marked with any information or had its tread pattern formed.
The green tire is placed into a mold, where heat and pressure are applied. As the rubber heats up, it expands to fill the mold, creating the tread pattern and imprinting the brand name, like Toyo Tires Proxes or Open Country.
However, during this process, air bubbles can get trapped between the rubber and the mold. These bubbles can prevent the tire from forming correctly. This is where the vent spews come in.
The mold has tiny tubes called spew holes or vent sprues, which allow excess air to escape as the rubber expands. These holes help ensure that no air bubbles form, allowing the tire to mold perfectly.
Steve Burke, the technical manager at Toyo Tires, explains why these little spikes are left on your new tires. “The air exits, ensuring that no air bubbles form between the tire and the mold, and it also carries out small bits of rubber.
This is how vent spews are produced. Most of the spews on the tread face are shaved off, but those on the shoulders and sidewalls of the tire often remain intact.”
So, should you remove these spikes? Steve says, “It doesn’t really matter. Vent spews don’t serve any purpose after the tire is made. Many show car owners take pride in shaving or trimming the nibs, but there’s no practical reason to remove them. If you want to, just grab them with your hand and pull them off—it’s actually quite effective stress relief.”
So, there you have it! Another mystery solved. Next time you get a new pair of Toyo tires, take a closer look at those vent spews, and you’ll know exactly what they’re all about.