We’ve spent plenty of time casually skating and occasionally trying out our hand at grinding a few rails. Skateboarding is one of the most adrenaline-pumping (and dangerous) ways of getting around the streets. We’ve only recently decided to take a look at what, exactly, makes up our skateboards. It’s a little more complicated than slapping a set of wheels onto a deck.
Not all wheels are the same, as we’ve found in our research. Skateboard wheels are made of polyurethane, a plastic-like compound that is easy to shape and has enough give to take even the most strenuous boarding. As you might guess, there are different kinds of polyurethane, each with a different level of hardness and suited for a different type of boarding.
Skating down the street requires something different than grinding or taking a few jumps on the halfpipe. In other words, you need a distinct blend of polyurethane. When you want to know "what are skateboard wheels made of?" the answer varies subtly depending on the wheel. First, we'll talk about polyurethane in general, then get into the different hardnesses of the wheels.
Polyurethane is a synthetic, somewhat elastic polymer. Without getting too deeply into the chemistry aspect of the substance, it starts as a liquid, similar to cast metal. The polyurethane gets poured into molds, where it cools and hardens into its desired shape: in this case, the wheels of the skateboard.
As you might guess from the name, polyurethane is a polymer, which is a substance made of repeating chains of pure compounds in each molecule. Think of it as an organic crystal lattice. Because the molecular pattern is relatively flexible between each compound, it lets the material flex under pressure and returns to its original cast shape.
History of Skateboard Wheels
When skateboards first came into existence back in the 1950s and 1960s, they had either steel or clay wheels. These materials, unlike polyurethane, offered no flex, so as you might imagine it could be quite a bumpy ride unless you rode on a street that had just been paved. The wheels also provided no traction.
In other words, if you wanted to change the direction you had to stop, point the board where you wanted to go, and start again. The wheels didn’t grip the road enough to turn without causing severe risk of tipping over and causing injury. It wasn’t until polyurethane wheels became widespread that riders could do anything on their boards.
Skateboard wheels come in three categories of hardness, each useful for different styles of skateboarding. We’ll talk about these and how they’re measured, as well as how to get the most out of your wheels. We’ll also discuss the various wheel profiles and sizes that exist and how they affect the performance of your ride. Every factor combines to produce a unique experience.
Therefore, when you want to know “What are skateboard wheels made of?” it’s also essential to understand their shape and composition. Some characteristics that influence performance are:
The hardness of a skateboard wheel is measured in durometers. Two different scales exist, delineated by A and B. The B scale is the same measurement, but extended by 20 points to accommodate measuring harder wheels. Here’s a rough breakdown of the hardness ranges.
78 - 88a: This is about the range you can be comfortable with for simple transportation down the road. The wheel has enough give to make any ride comfortable.
This range is what you want when you don't plan on doing any tricks or anything of the sort. This material is beneficial for getting you from point A to point B. The wheels, as they turn and are pressed down against the road by the weight of the rider, deform to the point that it almost feels like a flat surface.
89-98a: This is where you'll be if you're into doing a lot of aerial stunts. The wheels give you enough hardness to push off and get some air from the halfpipe, but it isn't so hard as to jar you on the landing. It's essential to be able to stick the landing and transition into the next technique.
99a and above: These are the hardest wheels, meant for grinding and leaping off hard surfaces like brick walls and staircases. The need to be hard so they can offer the most force feedback and keep you moving through the air. Otherwise, you won’t stick the landing.
The skateboard wheel profile is the shape of the wheel as it looks from the front or the back. Different wheel profiles have different effects on the performance of your deck. For example, an oval profile, where the corners of the wheels curve in gradually, makes it possible to make smooth turns.
Meanwhile, a more squared-off profile grips the pavement better but does not allow for the smoothest turns. The best thing you can do is try out different sets of wheels on your board and see what profile and style work best for your needs.
The wheel profile also can include tread. Deeper or differently shaped tread helps you grip to the pavement, whereas a smoother one will allow you to create smoother turns. You might not be able to stay on the sidewalk as well.
The width of the wheel is also called the contact patch. If you have an old-school longboard, you likely have an extremely wide contact patch. The larger the wheel is, the easier it is to get to high speeds.
Wheels come in different sizes, measured from 48 to 60mm. Smaller wheels have higher acceleration, meaning that they can get up to top speed faster. Wheels on the larger end of the spectrum accelerate more slowly, but they can reach faster speeds. It’s a sliding scale of inverse relationships.
Small wheels offer a little more control and balance than do larger ones, mainly because they are lower to the ground. Higher wheels have more power but less precision. Smaller wheels work best on smooth surfaces because the larger ones simply ride over the bumps.
Therefore, if you want to have a smooth ride even on rough surfaces, you’ll use large-diameter wheels.
On the medium part of the scale, you have wheels that are good for all-around use: street skating, skate parks, halfpipes, and more. They offer a balance between precision and speed. When you buy wheels, the seller should have an idea of what they should be used for.
Finally, small wheels work best for trick riding, especially in skate parks. Because the wheel is smaller, it’s lower to the ground. This closeness lets the rider feel subtle bumps and vibrations more quickly than otherwise, and they can adjust their footing or course accordingly. It’s similar to the idea of a tightrope artist wearing only socks on the high wire rather than socks and shoes.
Closer contact means a more acute sense of touch.
There’s no way to measure tear strength reliably, but you should at least know what it means. Tear strength refers to the effect friction has on the urethane of the wheel. As the wheel turns against the pavement, per Newton’s laws of motion the pavement is also ripping at the wheel, attempting to peel some of the outer layers of polyurethane off.
When this happens, it’s similar to the idea of tires wearing out on a car. Over time, the tire will peel away and expose the metal rim, or in the case of the skateboard, the plastic core. You can’t skate on that otherwise there would be a severe injury.
A tear strength that is too high creates an effect similar to hydroplaning: when the wheel comes loose from the pavement, it can suddenly grab it again after fishtailing. By this point, the board could be facing a new direction with or without a rider still on it. If it’s with, you’re in for a problem. If not, depending on where your board is, you could lose it.
Conversely, you don’t want too low of a tear strength, because it wears the wheel out quickly and makes you have to replace it faster. If you have a lot of money to spend on skateboard wheels and like the way these soft wheels feel, go ahead. However, if not, be prepared to spend dozens or even hundreds over time on a single piece of equipment.
If you’ve long wondered “What are skateboard wheels made of?” we hope that this article served as beneficial. Not only should you now know what material they’re made out of, but some of the physical characteristics of the wheels as well.
Even though skateboard wheels were once made of clay and steel, the transition to polyurethane has made it more profitable and stylish to ride around on boards for average transportation.