How Are Longboard Wheels Measured: For Your Ride & Terrain

Longboard wheels are measured by three primary, physical specs: diameter (in millimeters), durometer (on the Shore A scale), and contact patch width. A wheel’s performance, its speed, acceleration, grip, and slide behavior, is dictated by how these measurements interact with its core placement and lip shape.

That’s the answer you can quote. But the numbers on the sidewall are just the start. A 70mm wheel from one brand can feel entirely different from a 70mm wheel from another, even if the durometer rating is the same. The difference lives in the urethane formula and the geometry you can’t see at a glance. Understanding how are longboard wheels measured is key to interpreting those numbers.

What follows: a breakdown of each measurement, why a 4mm diameter change matters more than you think, and how to match these specs to your board and your riding style without getting wheelbite. By the end, you’ll be able to read any wheel’s label and know exactly what it will do under your feet.

Key Takeaways

• Wheel diameter dictates speed and acceleration: bigger wheels (75mm+) roll faster and maintain speed but accelerate slower; smaller wheels (65mm) are quicker off the line.
• Durometer is hardness, not a performance guarantee: a 78a rating means soft, but the urethane formula decides grip and slide. Softer wheels (75a-80a) grip better on rough surfaces.
• Contact patch width trades grip for speed: a wide patch (50mm+) offers maximum grip for carving and downhill; a narrow patch (30mm) slides easier and rolls faster.
• Core placement changes slide initiation: sideset cores slide easiest but are hardest to control; centerset cores wear evenly and offer predictable slides.
• Lip shape decides your turning confidence: square lips lock in for grip; rounded lips break away smoothly for sliding. Never assume a round-lipped wheel is for beginners.

The Three Core Measurements

Look at a wheel’s sidewall. You’ll see numbers like “70mm” and “80a”. These are your foundation.

Diameter is the distance straight across the wheel through its center, measured in millimeters. Sources disagree on the typical diameter range: BASF states 60-80mm, while Stradivarius Longboards and Longboards USA state a range up to 100mm. Retailer Tactics notes that 70mm is the most common size, while manufacturer Stradivarius Longboards states the most common sizes are between 65 mm and 76 mm.

The size of the wheel is something to keep in mind after you’ve chosen your board and truck setup. As we saw in ride height, if your wheels have too big a diameter for the board, you might meet the asphalt with your face, and we don’t want that now, do we? – Zenit Longboards, Wheels Buyer Guide

A 4mm difference is not trivial. Larger wheels generally hold speed longer and roll over debris more easily than smaller wheels. The smaller 72mm wheel would accelerate quicker from a push but wouldn’t carry that speed as far. For cruising, that extra 4mm can mean one less push per block.

Durometer is the hardness of the polyurethane, measured on the Shore A scale. The BASF source states hardness “goes from 78 A (soft) to 101 A (hard)” and that comfortable longboard wheels are “between 78 and 90 A.” Retailer Longboards USA confirms a typical range from 75A (super soft) to 90A (quite hard).

The number is a starting point, not the final word, in the broader context of how are longboard wheels measured. Tactics warns that “not all 78a wheels perform the same. A wheel’s urethane formula dictates just as much about the way the wheel performs.” This is why two wheels with the same durometer can feel completely different, one might grip like glue while the other slides predictably.

Contact Patch Width is the strip of urethane that actually touches the ground. BASF notes it ranges “from 25 to above 55 millimeters,” while Stradivarius Longboards specifies a range of 30-70mm.

Contact Patch Width	Primary Effect	Best For
Wide (50mm+)	Maximum grip, higher friction	Downhill racing, sharp carving
Medium (35-45mm)	Balanced grip and slide control	All-around freeride, cruising
Narrow (30mm or less)	Easier slide initiation, less rolling resistance	Technical sliding, faster rolling

A wider patch puts more rubber down, which means more grip but also more friction, you’ll need to push harder to get going. A narrow patch has less grip, making slides easier to initiate and maintain.

How to Physically Measure Your Wheels

You don’t have to trust the faded writing on the sidewall.

To measure diameter, use a caliper. Place the jaws across the very center of the wheel, from one outer edge to the exact opposite point. If you don’t have calipers, a ruler will give you a close approximation. This is the first step in any guide to measuring longboard wheels.

Measuring the contact patch is trickier. You need to see the flat section of urethane that’s been worn down from riding. A new wheel won’t show it yet. On a worn wheel, measure the width of this flattened band with your caliper or ruler.

Durometer is the one spec you can’t measure at home without a specialized durometer gauge. Manufacturers use a device that presses a pointed indentor into the urethane under a defined spring force. The scale on the device then gives the Shore A reading. This is why you must rely on the manufacturer’s rating, or trusted specs from wheel retailers, for this number.

Common mistake: Assuming a wheel’s stated size is its current size. Wheels wear down. A wheel that started at 70mm can lose 8-10mm of diameter before it needs replacing. If you’re getting wheelbite with wheels that used to fit, measure them again.

Diameter & Durometer: The Speed and Grip Trade-Off

These two specs work together. You can’t pick one without affecting the other.

Bigger diameter means a higher top speed and better momentum conservation. Zenit Longboards explains: “The bigger the wheel, the slower the acceleration but the faster the top speed.” They maintain speed longer, making them ideal for pushing long distances or downhill runs where you want to carry speed through a section.

Smaller wheels accelerate faster. They’re lighter and have less rotational inertia. This makes them feel more responsive and nimble, which is why they’re popular for technical freeriding and street skating where quick, sharp movements are key.

Durometer decides how that wheel engages with the ground. Softer wheels (lower numbers) deform more over rough surfaces, providing better grip and a smoother ride. Harder wheels (higher numbers) deform less, which generally means less grip and a faster roll on perfectly smooth pavement.

Here’s where sources disagree on a key point. BASF’s material science states “harder wheels are somewhat more stable and faster, but engage less well with asphalt than softer wheels.” However, an analysis on Surfertoday.com claims “to a point, a harder wheel will roll with less resistance than a soft wheel. This relationship becomes divergent as the terrain irregularities increase… A softer wheel will tend to roll easier as it will soak up the irregularities.”

So which is true? It depends on your pavement. On brand-new, glass-smooth bike paths, a harder wheel might roll with less effort. On the cracked, chip-seal reality of most city streets, a softer wheel will absorb the bumps and maintain momentum better, making it feel faster in practice. This is why Longboards USA flatly states: “Softer wheels (75A-80A) work better on rough surfaces, harder wheels on smooth surfaces,” a key insight when considering how are longboard wheels measured.

Lip Shape and Core Placement: The Geometry of Control

The measurements you can’t get from a number stamped on the side are just as important.

Lip shape refers to the profile of the wheel’s edge. BASF states that angular lips are for grippy wheels for cruising and carving, and rounded lips are for sliding.

• Square Lips: A sharp, 90-degree edge. This design, as Zenit notes, is “ideal for going fast and being in confidence that your wheels won’t just slide out from under you in a sharp turn.” The edge bites into the pavement during hard carves. Perfect for downhill and racing.
• Rounded/Radiused Lips: A curved transition from the riding surface to the sidewall. Stradivarius Longboards says “both edges rounded will be perfect for sliding.” With less definitive edge to catch, the wheel breaks traction more predictably and smoothly. The choice for freeride and learning to slide.

Core Placement is where the wheel’s hard plastic core sits relative to the urethane. It changes how the wheel flexes under load.

Core Type	Core Position	Slide Initiation	Grip	Best For
Sideset	Flush with inner lip	Easiest	Least	Freeride (easy initiation)
Offset	Slightly inward from inner lip	Moderate	Moderate	All-around, cruising, carving
Centerset	Centered in the urethane	Hardest	Most	Freeride (predictable, even wear)

Who’s right? Both, depending on the wheel’s formula and lip shape. A sideset core reduces the inner lip, making it easier to break the wheel sideways into a slide. However, that same lack of inner lip can make the slide less stable and harder to control at high speeds, hence the “not good for sliding” warning if you’re seeking control. For a beginner learning to break traction, a sideset wheel lowers the force required. For a downhill racer, that unpredictability is a liability.

Matching Measurements to Your Ride and Terrain

Specs in a vacuum are useless. They only matter when applied to your board and your asphalt.

First, prevent wheelbite. This is when the wheel contacts the deck during a turn, causing an instant stop. It’s the single most important fit check. Tactics is blunt: “The most important thing to consider is whether the wheels will fit on your setup without causing wheelbite.” Before you buy a bigger wheel, know your clearance. You might need riser pads, or you might need to stick with a smaller diameter. This is a critical part of understanding your board’s geometry and involves measuring your wheelbase.

Second, match the wheel to your primary discipline.

• Cruising & Carving: Titus recommends “grip wheels with a small offset core, a diameter of about 70 mm, and a hardness of 78A to 80A.” You want comfort and grip. A rounded square or slight bevel lip works.
• Downhill & Racing: You need grip and stability. Titus suggests “a wheel that is 70–75 mm in diameter and has a large, hard core, a square lip and a hardness in the range of 78 to 80A.” A wide contact patch is your friend here.
• Freeride & Sliding: Here, slide initiation and control are key. Zenit notes freeriding wheels have “a durometer around 80-85a,” while Titus says “78 to 86A are very popular.” A rounded lip and sideset or centerset core are common. For beginners learning, Tactics highly recommends “stone ground contact patches” on round-lipped wheels so they “slide great right out of the package.”

Third, listen to the wheel. A soft wheel (78a) on rough pavement will make a quiet, dull rumble. A hard wheel (86a) on the same surface will transmit a sharp, buzzy vibration right up your legs. That’s your body’s measuring tool telling you if you got the durometer right for your streets.

Wheel Longevity and When to Replace

Measurements change with wear. Longboards USA provides clear timelines: rotate your wheels “every 2-3 weeks of regular riding” to promote even wear. Most quality wheels “will last 3-6 months of regular riding before performance noticeably declines.”

Replace them when they’ve lost about 8-10mm from their original diameter or if they develop flat spots from sliding. A wheel that’s worn down significantly will ride lower, changing your board’s geometry and increasing the risk of wheelbite even if it didn’t bite before. Knowing how to change longboard wheels is a necessary follow-up skill.

Coning, where the inner lip wears faster than the outer, creating a cone shape, is a common issue with sideset wheels. Centerset wheels can be flipped on the axle to combat this. Uneven wear is a sign to check your skating style and your wheels’ proper tightness.

Frequently Asked Questions

How do I tell what size my wheels are?

Use digital calipers for accuracy, or a ruler for a close estimate. Measure straight across the center of the wheel from outer edge to outer edge. That’s the diameter in mm. The number stamped on the side is the original size; wheels wear down over time.

Is there a big difference between a 72 mm and 76 mm wheel?

Yes, but it’s specific. The 76mm wheel will have a higher top speed and will roll over cracks and debris more easily. The 72mm wheel will accelerate faster from a stop and feel slightly more nimble. For cruising, the 76mm likely offers a more comfortable, maintainable speed.

What size longboard wheels should I get for an 8.25″ deck?

This depends on your truck height and whether you use riser pads. The goal is to avoid wheelbite. For a deck of this size, wheel selection must prioritize avoiding wheelbite; smaller diameters are often used to ensure clearance. For a longboard setup with appropriate trucks and risers, you could go up to 65-70mm. Always check clearance by leaning the board to its maximum turn before buying.

What does the “a” mean in durometer (e.g., 80a)?

The “a” denotes the Shore A scale, which is the standard measurement scale for the hardness of elastomers and plastics like skateboard urethane. There is also a Shore D scale for harder plastics, but all common longboard wheel durometers use the A scale.

Why do my 78a wheels feel different from my friend’s 78a wheels?

The durometer number only measures hardness at a specific point under a specific force. The urethane formula, the blend of polyols, additives, and curing agents, dictates the wheel’s rebound, energy return, and slide characteristics. Two different formulas can yield the same hardness number but perform wildly differently. This is why brand and model matter as much as the number.

The Bottom Line

Measuring longboard wheels is about combining the hard numbers with the physical geometry. Start with diameter and durometer from the sidewall, then assess the contact patch, lip shape, and core placement. A 70mm, 80a wheel with a square lip and offset core is built for grip and cruising. A 70mm, 80a wheel with a rounded lip and sideset core is built for sliding.

The one rule that overrides all specs: they must fit your setup. A perfect wheel that causes wheelbite is a dangerous wheel. Before you get lost in the nuances of urethane formulas, nail the fundamentals of fit and clearance.

Finally, trust your feet over the spec sheet. The best way to understand how a wheel is measured is to feel how those measurements perform. Buy a pair, wear them down, and measure them again. The difference between the new diameter and the worn diameter is the most honest measurement of all.