It is good to know the tire size of your mountain bike. This way, you will be able to purchase a replacement tire whenever you need to. But to ensure that you are getting the correct tire size, you need to know the easiest methods to measure it accurately.
There are three methods to measure MTB tires:
- Standard method
- ISO method
- Circumference method
Methods one and two involve getting the diameter and width of the wheel to get the tire size. Meanwhile, the third method needs the circumference and diameter. (source)
How Are MTB Tires Measured?
Most bikers leave things up to their bike shop whenever they need to replace or upgrade their bike tires. That is understandable since things can get a bit tricky if you do them on your own.
Some people plan to shop online for a new tire as they are considering changing tires themselves. If you fall into this category, like I do, then you need to know how to measure the tires of your mountain bike properly.
When measuring your MTB tire, you can use a caliper or a tape measure to get the width and diameter. But if your mountain bike does not have a tire to begin with, you can measure the diameter or circumference of your wheel rim.
Keep in mind that most tires will state their size right on the sidewall, so you might be able to merely match what you’ve got. However, if worn, or if they are somehow unmarked, then take up one of the three measuring methods.
Although it can be hard to make out, the tire should have a number embossed on it like 26 x 2.1 or similar. This is the tire size, where 26 means 26-inches and the 2.1 means the width is 2.1-inches.
Measuring MTB Tire Using the Standard Method
1. Put the bike in an upright position.
One tip for securing the bike in an upright position is to lean it against a wall or to use the kickstand. After putting the MTB in place, you can measure its wheel without worrying that the bike might tip on you.
The best solution though, is to mount the bike on a repair stand like the Bike Hand Repair Stand. I’ve got one of these and it works fantastic to hold the bike up so you don’t have to bend over, stressing my back.
If you do not have anyone to help you measure the bike’s wheel, it is better to use a retractable tape measure instead of a plastic tape measure. This way, you will have your other hand free, allowing you to record the measurements.
2. Measure the distance from the outside edge of the tire (where it would contact the ground) to the center of the wheel
Measuring the distance of the ground just beneath the bike’s tire to the center of the wheel will allow you to get the tire’s radius. Multiply that measurement by two, so you can get the diameter.
3. Get the measurement of the tire’s flat part.
The distance from one edge of the tire to the other indicates its width. It can significantly differ depending on the type of tire your mountain bike has. For instance, if you have a flat tire, then you will get a wider width measurement.
Generally speaking, the wider the treads, the rougher the terrain that the tires are intended. On the other hand, narrow treads indicate a smoother and faster ride.
After getting the measurement, the next thing to do is to purchase a new tire. When buying from a local store or online, remember to put the diameter first before the width.
For instance, a tire with a size of 26 x 1.75 means that it has a 26-inch diameter and 1.75-inch width from one side of the tread to another.
Measuring The Tire Using the Iso Method
1. Check if your MTB’s wheels are measured using the ISO system
The ISO or International Organization for Standardization is a measuring system that uses millimeters to determine your MTB’s wheel size. If your measuring tape does not have metric rules, remember that an inch consists of 25.4 millimeters. You can determine the width of the tire in millimeters by multiplying inches by 25.4.
For example, if you get a tire size of 27.5 inches, you can multiply that by 25.4. The result will be 698.5, which is the measurement of your tire in millimeters. (source)
Notably, ISO sizing is the most reliable option in terms of measuring your tires by yourself. It will give you the most accurate measurement. Some tires have a measurement of both standard and ISO methods.
In addition, you should see the tire size printed on the side of the tire, as you can see in the picture earlier in this article. If you’ve ever seen or heard of a 700 sized tire, that’s the ISO (millimeters) size.
2. Measure the tire
Using the exact measurement method above, measure the radius from the center of the wheel up to the tire’s outer edge. You can also get the wheel’s width using the step mentioned above, only that you need to use millimeters.
If you really want to be precise when it comes to tire width, you can use a Vernier to determine the exact width in millimeters.
Measuring the MTB Tire Using the Wheel’s Circumference
1. Get the wheel’s measurement.
The circumference of your mountain bike’s tires is the distance around the outer part of the wheel. It would be best if you had this measurement to calibrate the bike’s speedometer, odometer, computer, or GPS.
You can calculate the circumference, or measure it directly using a non-stretching string or cord. Roll the cord around the outermost edge of the tire. Mark the string or cord at the exact point it meets with itself after a full rotation. Now, measure your string on a tape measure to get the circumference.
This method of using a string or cord is quite rudimentary, so you might want to be more precise via a calculation. Here’s how to do that:
2. Calculate the circumference
After getting the wheel’s diameter, you can calculate the circumference by multiplying the diameter by pi.
Pi is equal to 3.14 (and a bunch of other numbers, but we can leave it at 2 digits for this). So, if you have a 26-inch MTB tire, you can calculate the circumference by multiplying 26 by 3.14. The result, which, in this example, is 81.64 inches, is the circumference of the tire.
If you cannot measure the diameter of your wheel, you can use a string to measure the circumference instead, as mentioned previously.
Regardless of the method that you used to measure your tires, you need to note that:
- A cross-country bike generally has tires with a width range of 1.9 inches to 2.25 inches.
- All-mountain and trail bikes have tires with a width range of anywhere from 1.9 to 2.4 inches.
- Downhill bikes are intended to endure the abuse of repeated drops and rocks. Typically, they have tires that measure up to 2.5 inches wide.
Finally, fat-tire bikes, which cyclists can use for all-season riding, have tires that can measure from 3.7 to 5 inches or more. (source)
Types of Mountain Bike Tires by Riding Style
No tires are created equal. Meaning you can never find a bike tire that excels in everything.
For this reason, you need to focus on the features that are most crucial for your riding style.
Here are the different riding styles and the mountain bike tires that work best for them:
For cross-country mountain bikers, climbing efficiency is a lot more critical than extra durability or traction. That said, you need to look for mountain bike tires that are lightweight and can roll fast. You can opt for smaller and more densely spaced tread patterns.
You can use an all-around tire for trail riding. But it is essential to make sure that you are getting one with a moderate level of traction, speed, and durability.
Downhill riding means you will get a lift to the top. For this reason, you need to ensure that your MTB tires are busty and tenacious. This way, you will have a ride fueled by gravity but controlled by beefy tread.
In addition, you need a set of tires that can withstand stick landings and some abuse. They should also be able to claw their way around every turn.
All-mountain riding focuses on descents, although you still have to ride to the top. For this type of biking, what you need is a set of tires that can grip well whenever you take turns at a fast speed.
The tires of your mountain bike also need to be capable of withstanding moderate impacts. For this reason, it is ideal that all-mountain bikers look for tires with more prominent side tread. One great tire type for this type of riding is a fat tire you can use for all-season trail riding. However, fat tires will slow you down on the ascent, so a rugged and beefy all around tire with decent tread may be the best option here. (source)
Learning about Mountain Bike Tires could take years. Let me help you just a bit quicker with some articles.
- Can a tire be great for both street and trail? – Find out in this article: Best MTB Tire for Street and Trail
- Are 26 inch Tires Dead? Heck no…Read – Who is a 26 inch MTB For
- Love playing in MUD – Read What tire is recommended – Mountain Bike Tires for Muddy Conditions
- Rocks can destroy a mountain bike tire – Find the Best MTB Tire for Rocky Conditions (PRO ROCOMMENDED)
- Thinking about getting a 26 inch MTB let me help – Should I Get a 26 Inch Mountain Bike?
- Does sand slow you down? It might be you’ve got the wrong tires. Read – The Best MTB Tires for the Sand
Features To Look for When Replacing Your MTB Tire
After getting your mountain bike tire’s size, the next step is to purchase your replacement tire. But before doing so, there are two features that you need to look at:
Many trails that cyclists ride when mountain biking have jagged rock edges and sharp objects waiting to puncture your tire. For this reason, many mountain bikers prefer to add a little weight to add protection to their tires.
True enough, durable rubber helps in making your MTB tire more durable. However, the primary factor for puncture protection relies upon the casing.
While you think that having a 2-ply tire is enough, adding reinforcements made of protective materials like Kevlar is a lot better.
Manufacturers have done a lot of research and development to make strong rubber compounds. These manufacturers are trying to balance contradictory goals – long wear, good grip, and low rolling resistance.
For better grip, the tire needs to have soft compounds. On the other hand, hard rubber will last a long and will provide you with lower resistance.
Most of the time, race tires utilize a single compound that provides riders with superior grip. However, single compound tires usually wear out after a couple of rides.
Meanwhile, the typical design solution for non-racing tires involves a dual-compound rubber. These tires have harder rubber in the center that allows the tire to last longer and roll faster. But the sides of the tire are the most critical part because they are softer and have more traction. (source)
Tips for Purchasing a Mountain Bike Tire
Begin with only one set of tires
Most mountain bikers have tire sets for different situations. But if you are not used to multiple sets, you can start with a single set of new tires.
However, you need to thoroughly think about where and how you are going to ride usually. After determining this factor, focus on the most challenging types of riding and the terrain you plan to tackle.
Determine if you want to mix and match tire sets
Mixing and matching tire sets all boils down to your personal preference. Some riders want a tire that has more traction in front while the back has less rolling resistance. On the other hand, other mountain bikers like the same surefootedness everywhere.
Regardless of your preference, you can try it one way and experiment with different tire types to suit your individual riding style.
Consider the tread pattern.
The tread pattern is the art and science side of mountain bike tires. For instance, pointy knobs will provide you with a better grip compared to smooth and short knobs. So, the way that your tire looks is also important when choosing which you will purchase.
In addition, make sure that you take note of knob spacing. The reason is that it can affect the grip and mud-shedding properties of the tire.
The lipped edge of the tire located inside your rims is the tire bead. For tire bead, you have two choices – Kevlar or wire bead.
If you want a tire bead with a lighter weight, you can opt for Kevlar. However, you need to note that this type typically adds up the price of the tire.
Kevlar tires are also foldable. For this reason, it can be more challenging to mount compared to a wire bead tire. However, wire bead tires can be a little tricky to get over the rim. I recommend you make sure you have a good Tire Wrench. I love my Park Tool Tire Wrenches (link to Amazon), the wrench is plastic coated metal. The plastic protects your rim and the metal provides the strength.
I’ve talked mentioned my bike tool kit in the past, Bikehand Bike Repair Tool Kit (link to Amazon and highly recommended) has tire wrenches and other “specialty” tools needed for keeping your bike in good running order.
Tubeless or tubed?
Some manufacturers market tubeless, tubeless-ready, or UST tires. Notably, UST means you can use the tire with a tubeless wheel set up.
However, it is essential to note that there are pros and cons to running tubeless. So, before choosing this option, make sure that you are aware of what you are getting.
Either way, you’re going to need to ensure you’ve got decent tire pressure. Checking your tire pressure is critical to being properly setup for a good ride. Make sure you’ve got a good tire gauge to double check that psi.
Talk to a professional
Professionals who know a lot about mountain bikes and MTB tires are well aware of what will work best for you. So, if you are not sure about what you want to get, try talking to an expert, so they can make recommendations about what tires your mountain bike needs to have.
That said, you can make sure that you are getting what you paid for and the tires you purchased are meeting your needs and requirements.
David Humphries is the creator of DIY Mountain Bike. For me a relaxing day involves riding my mountain bike to decompress after a long day. When not on my bike I can be found wrenching on it or casting a fly on a small mountain stream. Read more about David HERE.