How to measure skateboard wheels?

Skateboard wheels come in sets of four, and they each need eight bearings, which are sold separately. Each wheel has two bearings built into it. This lets the wheel spin freely on the axle of a truck.
The diameter of a skateboard wheel is always measured in millimeters, and the density of a wheel is measured by its durometer on a “A Scale” or “B Scale,” which shows how hard it is.

We think that 52mm wheels, an 8″ board, and 139 or similar-sized trucks are a great place to start. But wheels come in many different sizes, shapes, and colors, and like everything else in skateboarding, what you like is what matters most.

How big should my wheels be?

Most skateboard wheels are between 48mm and 60mm in size, and different sizes are better for different types of skating or terrain.

Your skateboarding hardware and equipment choices will change as you get better, but here’s a general idea of how different-sized wheels work best:

  • Small (wheels between 48mm and 51mm)

Smaller skateboarding wheels are suitable for skating flatground. In the 1990s, wheels under 50mm were very popular, but now most wheel companies start measuring at 50mm.

Small skateboard wheels are more likely to get stuck in cracks or on rocks, but wheel bite is less likely because there is more space between the wheel and the board.

  • Medium [52ml to 54ml wheels]

This size of wheel is good for all kinds of street and transition skating. All of the wheel brands we carry make wheels in this size range, and they come in different styles and hardnesses. If you’re building your first complete skateboard, we recommend starting with a 52ml wheel.

  • Large [55ml – 60ml wheels]

Bigger wheels have more surface area, which makes the whole thing more stable. More contact with the ground also makes it easier to keep speed, which is why ramp and vert skateboarders usually choose bigger wheels.

Even though they can change the weight of a skateboard and you might need risers to stop wheel bite, larger wheels are less likely to get stuck in cracks or small things.

  • Cruiser, Longboard & 60ml + wheels

Most wheels over 60ml have a very low durometer, which makes them easy to ride on even the roughest roads. This type of wheel isn’t good for doing tricks, so they are usually found on cruisers, longboards, and other skateboards that aren’t in the shape of a popsicle.

What does it mean to say “durometer”?

The hardness of skateboard wheels is measured by a tool called a durometer. Usually, a “A Scale” is used to measure them. Most manufacturers use this 100-point gauge. However, they also use the B Scale, which is 20 points lower than the A Scale. For example, a 100a wheel is about as hard as an 80b wheel.

Low durometer wheels are softer, grip more, and make for a smoother ride. High durometer wheels, on the other hand, are harder, grip less, and give a more natural sense of speed when riding.

Most companies that make skateboard wheels offer wheels with different hardnesses and formulas that are clearly made for different types of skating. For example, Bones STF and Spitfire Formula Four 101D are hard wheels for street skating, while Bones SPF and Spitfire Formulas Four 99D are better for transition and ramp skating.

There are different shapes and styles of skateboarding wheels.

Skateboard wheels all do the same thing, but you can choose from a lot of different shapes and sizes. At Black Sheep, we always suggest checking out a product in person, where our staff is happy to help and give advice. Here’s a rundown of the different types of wheel shapes we carry, though:

  • Normal/Standard

A “normal”-shaped skateboard wheel has a small contact area (the part of the wheel that touches the surface) and beveled edges that are slightly curved. Every wheel brand we carry has this style, and some wheel brands only have one shape in their whole line.

  • Conical

Conical skateboard wheels have a larger contact area and very slightly curved sidewalls. This is helpful for skate ramps because it makes it easier for skateboarders to lock into the coping.

  • Radial

Radial wheels on a skateboard are the opposite of conical wheels. They have a larger contact area and edges that are more strongly beveled than regular wheels. This gives more space between the wheels and the ground, making the ride smoother even on the hardest surfaces.

  • Core

The “core” of a skateboard wheel is a separate area, usually made of plastic, that holds the bearings. Sometimes the core will look like the spokes in a bicycle wheel, while other times it will be less obvious. They are made to have a softer hardness without affecting the stability of the bearings. They can also be lighter than other skateboard wheels.

  • Cruiser

The very low durometer of these wheels makes for a smooth ride. Most of the time, they are not made for skateboarding tricks, but you can find them on vinyl cruisers, old school setups, and longboards.

What are the wheels on a skateboard made of?

Polyurethane is used to make the wheels for skateboarding. Before urethane wheels were made in the late 1960s, skateboarders used roller-derby or clay wheels to keep their boards moving. After urethane was invented, it became the standard material for making skateboard wheels quickly, and the rest is history.

What do flatspots mean?

Flatspots are flat spots on a wheel that form as the wheel is used. Some flatspots are easy to see, while others are almost impossible to see. However, skateboarding wheel manufacturers are always working to make wheels that are less likely to get flatspots and are of higher quality.


Flatspots do not mean that your wheels are broken. They are a normal part of a skateboard’s wear and tear, and they happen when the board is used often, when it gets caught on something that makes it move without the wheel turning, or when you do a power slide.