How to Measure the Size of a Mountain Bike Wheel

By: Alex Bristol

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How to measure the size of a mountain bike wheel

Replacing your mountain bike wheels but unsure of which ones you need to get?

Let me give you a hand with that one. Before you can go ahead and change the wheels, you need to know which ones you have and what the options are for you, or you could be stuck.

I’ve been asked this question a few times, and the good news is that it has a simple answer. Once you know, you’ll be able to figure out exactly what you need.

You may be wondering, how do I work out the width and diameter of my tires? what mountain bike wheel sizes are there? How do I find out what size I need?

To summarise, Mountain bikes come in 26 inches, 650b (27.5 inches) 29inches and 27.5+. You probably have one of these on your trusty mtb, but may need a little help identifying it.

From identifying your tire markings to measuring the diameter and width of your wheels, here is everything you need to know about the wheels on your mountain bike wheels.

Bike tires explained

How to measure the size of a mountain bike wheel? There are two main parts to measuring your bike tire.

Tire diameter- this is usually measured in inches and will be the biggest number. There are different diameters you can choose from.

Tire width- This is also in inches and is a smaller number. Normally ranges from 1.75 to 2.215.

Related to this, the international measurement used for any bike is the ISO, which stands for Internation Organization for Standardization. The ISO number is a system that uses millimeters for the width and edge inner diameter or bead seat diameter.

You will find the ISO and the measurements imprinted on one side of the tire of your bike, which makes it easy to find.

Measuring Mountain bike wheels

Now, let’s have a look at measuring the entire wheel size, this includes the tire and the rim diameter. When we talk about 26 inches or 27.5 inches or 29 inches, this all refers to wheels not tires. That means your tire’s thickness and rim diameter combined, meaning you’ll need to manually measure them if you can’t see these numbers on the tire.

Step 1 – Read your tires

In step 1 you need to check the side of either the front or back tire for a set of numbers printed on the tire itself. In most cases, you will find numbers for example 26 x 1.5 Inch or something close to that. This measurement means that the wheel size is 26 inches and it has a 1.5-inch tire.

The good thing about this method is that it is very easy to interpret. These measurements, although imprinted on the tire, give you the total size with the wheel rim included.

This is the usual way of checking your wheel size. However, if you can’t see those numbers, follow the next few steps to determine the correct size of the wheel.

Step 2 – Secure the wheel

For step 2 hold the tire and the rim together in place. It might not be possible to do it alone so you need someone to help you or flat against the wall. Whatever system works for you.

Step 3 – Grab a tape measure

Step 3 involves placing a yardstick in a flat line against the outer end of the bike tire. After this, use a measuring tape to determine the length of the tire and rim. Measure the distance between these two points.

You should place the measuring tape on top of the axle when measuring the widest point of the wheel. Push the measuring tape end against the yardstick to confirm that you are getting the correct measurements.

Step 4 – Find your size

Step 4 is the final step. Check the readings at the end of the measuring tape opposite to the yardstick. A standard mountain bike wheel has a measurement length of 26 inch. Some have a measurement of 27.5 inch while others measure 29 inch.

Buying a tire for your mountain bike

Now that you know what size wheels you need, how do you go about choosing the right tire for your mountain bicycle wheel for your ride?

First of all, make sure that you’ve measured the distance from the axle assembly, in other words, the hub and the outer edge of the bike tire’s rims or bead.

Next check if you have this measurement in inches or millimeters. Make sure you measure correctly. For mtb bikes, the tire size will need to be in inches. Here’s a tip- take a look at a bike chart and match this measurement to the appropriate rim size.

Now you need to find the right tire size for your rim size by looking at the sidewall of the tire. There you will see the size is written for example 26 inch (tire diameter) x 1.75 (tire width) so 26 x 1.75

The tire you pick up needs to match the first number on your tire needs to your rim size.

Then select the tire based on your preference. A lot of bikes will have a width of 1.95 inches for cross country riding or you can use 2.35 for downhill riding. Have a look at the style of mountain biking you do to select your tires, it can make a big difference.

Differences between wheel size

With all of these sizes in mind, you need to determine your preference for wheel and ride style. Maybe you’re thinking of buying a new bike, so which size should you go for?

Features of 26 Inch Wheels

Why buy 26 inch wheel size? These ones are the most common and their greatest benefit is that it is very easy to find their spares as compared to other sizes. They have the following features.

  • You can easily adjust their weight, stiffness, and strength.
  • Their spare parts are very cheap as compared to other sizes.
  • They are easier to use on rough terrains than larger wheels.

Features of 27.5 Inches Wheels

What you need to know is that these wheels are not exactly 27.5 inch but they are around 27 inches. This makes them easier to flick and faster when accelerating on your ride. They are also suitable for rough terrains. Other features include.

  • Faster when accelerating
  • They are stiffer and stronger than the 26 inches wheels.
  • Not as easy to find their tires, wheels and other spare parts.

Features of 29 Inches Wheels

These ones are the biggest and are not easy to use on pump tails as compared to other sizes. Some of their noticeable features include;

  • Smoother and more stable than the smaller wheels. As a result, they provide better control on rough terrain.
  • Slower to move
  • Harder to  use for short riders

Frequently Asked Questions

Can you put regular tires on a mountain bike?

No, they are not related. Your mountain bicycle rims are designed to be compatible with a range of widths, but some are only suited to mtb. It will largely depend on your current mountain bike size.

How do I choose a mountain bike tire?

Depends on the kind of riding style you do. For cross country, I recommend going for climbing efficiency and fast, lightweight wheels for your bicycle. For trail riding go for some general all round tires with a good level of traction, durability, and speed.

Are wider tires better?

They have pros and cons. In dry conditions on the ground, wider tires will have better traction than narrow tires. They also offer more stability but are not as good if you want to go faster or want something light.

Should I get 27.5″ or 29″ mountain bike tire?

27.5 tires are much better for acceleration and are lighter, so if you’re going for speed this is better. However, if you tend to do more rough trails, then the 29 tires have good traction and better attack angle than the smaller tires. They will be a bit heavier and not as fast, however.

How much do mtb tires cost?

Mountain bike tires tend to be lightly overpriced compared with regular road or hybrid bike tires. They can range from $30 all the way up to over $100. That being said, I would recommend investing in a good quality pair as these will last you a good while before you need to replace them.

Final Thoughts

One of the most important aspects you should check when buying a mountain bike is the size of the wheel.

In my opinion, everybody should learn how to measure their bike wheel. Wheel size is not only important when you need to change your tires, but also when determining which bike to buy and the style of cycling you enjoy.

Whether you’re looking for fast tires or strong grip tires, the wheel size can have a strong impact on these factors.

If you are searching for strong or more powerful bikes, then riders need to consider any of those with short wheels which means that those with 26 inches wheels are the best.

Another benefit of using them is that their spare parts are readily available and are also cheap. However, for those searching for mountain bikes they can use for cross country, then the larger wheels are better due to their stability.

I personally love experimenting with new wheel sizes, and now that you know how to measure your mountain bicycle wheel, which size will you be trying out?

If this article was helpful, then check out my other related article on mountain bikes on this website!


1. BMX BIKE SIZING GUIDE– Post by Evans cycles