Bike Tire Sizes Explained

Where can you find your bike tire size?

Finding your bike tire sizes is quite easy since they are generally displayed on the tire sidewall.

But what may be more confusing for some is what these tire sizes correspond to, as they can be expressed in three different ways: ETRTO, imperial or metric measurements. Let us shed some light on each of them.

Understanding bike tire sizes

Look for the numbers appearing on the tire wall. You may need to spin the wheel round until you can see them, but they should still be quite easy to spot.
Your bike tire size will probably be given in one of these three ways:

ETRTO bicycle tire size measurements

ETRTO bicycle tire sizes appear as two digits separated by a dash: For example, 23-622, 25-622 or 28-622. The bike tire size meaning is deciphered as follows:

23-622 / 25-622 / 47-622

The first digit is the tire's width in millimetres at a given pressure and rim width. So, for instance, a typical road bike tire size would display a smaller first pair of digits than a mountain bike (see mountain bike tire sizes explained). Michelin follows the ETRTO recommendations.

23-622 / 25-622 / 47-622

For now, it’s important to understand that the second, three-digit number of an ETRTO bicycle tire code relates to the rim ‘s seat diameter – again expressed in millimetres.

Keep in mind that the ETRTO measurement is the least used regarding the choice of your bicycle tire.

Imperial bicycle tire size measurement

Some cyclists are more familiar with the imperial measurement. It is shown as a sequence of numbers like for example: 29 x 2.10 or 29 x 2.25. This type of measurement is usually used for mountain bike & city tires.

29 x 2.10 or 29 x 2.25

Here, the bike tire sizes are given in inches. The first number states the overall diameter (including the tire) at a given pressure and rim width. The term 29 inches is often used to define the rim’s seat diameter. But that’s not the case, 29 inches is the overall diameter including the tire.

29 x 2.10 or 29 x 2.25

The second number gives the width of the tire mounted on the rim. So, in the examples above, 2.10 represents two-and-a-tenth inches, while 2.25 represents two-and-a-quarter inches at a given pressure and rim width.

Imperial bicycle tire sizes sometimes have three numbers:

22 x 1 3/8 x 1 1/4

When this happens, the first number always corresponds to the overall diameter in inches. Then, the second number give the tire height and the final number represents the tire's width. So, in the example given, the tire would have a diameter of 22 inches, a height of one-and-three-eighths of an inch, and a width of one-and-a-quarter inches. That's why using Michelin's bike tire size guide for cyclists can be very helpful for understanding bicycle tire sizes

Metric bicycle tire size measurements

Last but not least, cyclists will often encounter tires with markings such as 700 x 23C or as 700 x 28B, for example. This sizes, which are in millimetres, are often used for road tires measurement.

700 x 23C or as 700 x 28B

Here, the first number is the overall diameter of the tire at a given pressure and rim width.

700 x 23C or as 700 x 28B

The second part indicates the tire's width in millimetres, plus the rim size expressed by a letter code.

Do you find all this complicated? Don’t worry! Since you can find different type of measurements for the same tire, Michelin provides a bike size chart to help you convert one measurement to another, as we will explain below.

Bike tire size chart: How to convert a measurement?

In our bike tire size chart, there are 3 columns, one for each measurement, which makes it easy to convert bike tires sizes from metric to imperial / or vice versa. You can also use the bike tire size chart to convert ETRTO (European Tire and Rim Technical Organisation) bicycle tire size data to one of the other types. This way you will find the correspondence between the measurement indicated on your tire and that indicated for the tire you wish to buy.

See below our Bize tire size chart.

‎ Bike tire size chart

12"
ETRTO	INCHES	mm (millimeters)
47-203	12 x 1.75	-
-	12 x 1.90	-
-	12 1/2 x 1.75	-
-	12 1/2 x 1.90	-
50-203	12 x 2.00	-
54-203	12 x 1.95	-
57-203	12 1/2 x 2 1/4	-
62-203	12 1/2 x 2 1/4	-

14"
ETRTO	INCHES	mm
47-254	14 x 1.75	-
-	14 x 1.90	-
50-254	14 x 2.00	-
40-279	14 x 1 1/2	350 x 38B
37-288	14 x 1 3/8	350 x 351
-	14 x 1 5/8 x 1 3/8	-
40-288	14 x 1 5/8	350 x 38A
44-288	14 x 1 5/8 x 1 3/8	350 x 42A
47-288	14 x 1.75	-
32-298	14 x 1 1/4	350 x 32A

16"
ETRTO	INCHES	mm
40-305	16 x 1.5	-
47-305	16 x 1.75	-
-	16 x 1.90	-
50-305	16 x 2.00	-
54-305	16 x 1.95	-
-	16 x 2.00	-
57-305	16 x 2.125	-
40-330	16 x 1 1/2	400 x 38B
28-340	-	400 x 30A
32-340	16 x 1 3/8 x 1 1/4	400 x 32A
37-340	16 x 1 3/8	400 x 35A
44-340	16 x 1 5/8	-
28-349	16 x 1 1/8	-
30-349	16 x 1.20	-
32-349	16 x 1 1/4	-
-	16 x 1.25	-
35-349	16 x 1.35	-
37-349	16 x 1 3/8	-

17"
ETRTO	INCHES	mm
32-357	17 x 1 1/4	-
32-369	17 x 1 1/4	-

18"
ETRTO	INCHES	mm
28-355	18 x 1 1/8	-
32-355	18 x 1.25	-
35-355	18 x 1.35	-
40-355	18 x 1.50	-
42-355	18 x 1.60	-
47-355	18 x 1.75	-
-	18 x 1.90	-
50-355	18 x 2.00	-
37-387	18 x 1 1/2	-
28-390	18 x 1 1/8	450 x 28A
37-390	18 x 1 3/8	450 x 35A
55-390	-	450 x 55A
57-390	-	450 x 55A
37-400	18 x 1 3/8	-

20"
ETRTO	INCHES	mm
54-400	20 x 2 x 1 3/4	-
23-406	20 x 0.90	-
25-406	20 x 1.00	-
28-406	20 x 1.10	-
-	20 x 1 1/8	-
32-406	20 x 1.25	-
35-406	20 x 1.35	-
37-406	20 x 1.40	-
-	20 x 1 3/8	-
40-406	20 x 1.50	-
42-406	20 x 1.60	-
44-406	20 x 1.50	-
-	20 x 1.625	-
47-406	20 x 1.75	-
-	20 x 1.90	-
50-406	20 x 2.00	-
54-406	20 x 2.10	-
-	20 x 2.00	-
55-406	20 x 2.15	-
57-406	20 x 2.25	-
-	20 x 2.125	-
60-406	20 x 2.35	-
54-428	20 x 2.00	-
40-432	20 x 1 1/2	-
37-438	20 x 1 3/8	-
40-438	20 x 1 3/8 x 1 1/2	-
28-440	-	500 x 28A
37-440	-	500 x 35A
40-440	20 x 1 1/2	500 x 38A
23-451	20 x 0.90	-
-	20 x 7/8	-
25-451	20 x 1.00	-
28-451	20 x 1 1/8	-
37-451	20 x 1 3/8	-

22"
ETRTO	INCHES	mm
50-489	22 x 2.00	-
28-490	-	500 x 28A
32-490	22 x 1 3/8 x 1 1/4	550 x 32A
37-490	22 x 1 3/8	550 x 35A
47-498	22 x 1 3/8 x 1 1/4	-
25-501	22 x 1.00 B.S	-
32-501	22 x 1 1/4	-
37-501	22 x 1 1/4	-

24"
ETRTO	INCHES	mm
40-507	24 x 1.50	-
44-507	24 x 1.625	-
-	24 x 1.75	-
47-507	24 x 1.75	-
-	24 x 1.85	-
-	24 x 1.90	-
50-507	24 x 2.00	-
-	24 x 1.90	-
-	24 x 2.125	-
54-507	24 x 2.10	-
55-507	24 x 2.15	-
57-507	24 x 2.25	-
-	24 x 2.125	-
60-507	24 x 2.35	-
62-507	24 x 2.40	-
23-520	24 x 0.90	-
-	24 x 7/8	-
44-531	24 x 1 5/8 x 1 1/2	-
40-534	24 x 1 1/2	-
20-540	24 x 3/4	-
23-540	24 x 0.90	-
-	24 x 7/8	-
25-540	24 x 1.00	-
30-540	24 x 1.20	-
32-540	24 x 1 3/8 x 1 1/4	-
37-540	24 x 1 3/8	-
40-540	24 x 1 3/8 x 1 1/2	-
22-541	-	-
25-541	-	600 x 25A
28-541	-	600 x 28A
32-541	24 x 1 3/8 x 1 1/4 NL	600 x 32A
37-541	-	600 x 35A

26"
ETRTO	INCHES	mm
20-559	-	-
23-559	26 x 0.90	-
-	26 x 7/8	-
25-559	26 x 1.00	-
28-559	26 x 1.10	-
30-559	26 x 1.20	-
32-559	26 x 1.25	-
35-559	26 x 1.35	-
37-559	26 x 1.40	-
-	26 x 1 5/8 x 1 3/8	-
40-559	26 x 1.50	-
42-559	26 x 1.60	-
44-559	26 x 1.625	-
44-559	26 x 1.75	-
47-559	26 x 1.75	-
-	26 x 1.80	-
-	26 x 1.85	-
-	26 x 1.90	-
-	26 x 2.00	-
50-559	26 x 2.00	-
-	26 x 1.90	-
-	26 x 1.95	-
52-559	26 x 2.00	-
54-559	26 x 2.10	-
-	26 x 1.95	-
-	26 x 2.125	-
57-559	26 x 2.25	-
-	26 x 2.125	-
-	26 x 2.20	-
58-559	26 x 2.35	-
62-559	26 x 2.40	-
-	26 x 2.50	-
64-559	26 x 2.50	-
65-559	26 x 2.60	-
70-559	26 x 2.75	-
75-559	26 x 3.00	-
95-559	26 x 3.70	-
-	26 x 3.80	-
100-559	26 x 4.00	-
115-559	26 x 4.50	-
120-559	26 x 4.80	-
20-571	26 x 3/4	-
23-571	26 x 7/8	650 x 23C
40-571	26 x 1 1/2 CS	650 x 38C
-	26 x 1 3/8 x 1 1/2 NL	-
47-571	26 x 1 3/4	650 x 45C
-	-	650 CS Confort
54-571	26 x 2 x 1 3/4	650 x 50C
20-590	26 x 3/4	650 x 20A
25-590	26 x 1.00	650 x 25A
28-590	26 x 1 3/8 x 1 1/8	650 x 28A
32-590	26 x 1 3/8 x 1 1/4	650 x 32A
37-590	26 x 1 3/8	650 x 35A
40-590	26 x 1.50	650 x 38A
-	26 x 1 3/8 x 1 1/2	-
42-590	26 x 1 5/8	650 x 40A
32-597	26 x 1 1/4	-

27"
ETRTO	INCHES	mm
40-609	27 x 1 1/2	-
20-630	27 x 3/4	-
22-630	27 x 7/8	-
25-630	27 x 1.00	-
-	27 x 1 1/16	-
28-630	27 x 1 1/8	-
32-630	27 x 1 1/4	-
35-630	27 x 1 3/8	-

27,5"
ETRTO	INCHES	mm
28-584	26 x 1 1/8 x 1 1/2	650 x 28B
32-584	-	650 x 32B
35-584	27.5 x 1.35	650B
-	26 x 1 3/8 x 1 1/2	650 x 35B
37-584	27.5 x 1.40	650B
-	26 x 1 1/2 x 1 3/8	650 x 35B
-	-	650 Standard
40-584	27.5 x 1.50	650B
-	26 x 1 5/8 x 1 1/2	650 x 38B
44-584	27.5 x 1.65	650B
-	26 x 1 5/8 x 1 2/2	650 x 42B
-	-	650B Semi-Confort
-	-	650B 1/2 Ballon
50-584	27.5 x 1.75	650B
52-584	27.5 x 2.00	650B
54-584	27.5 x 2.00	650B
-	27.5 x 2.10	-
55-584	26 x 1 1/2 x 2	650B
58-584	27.5 x 2.25	650B
61-584	27.5 x 2.35	650B
64-584	27.5 x 2.40	650B
66-584	27.5 x 2.50	650B
70-584	27.5 x 2.60	650B
71-584	27.5 x 2.75	650B
74-584	27.5 x 2.80	650B
75-584	27.5 x 2.90	650B
-	27.5 x 3.00	-7,5

28"
ETRTO	INCHES	mm
18-622	28 x 3/4	700 x 18C
19-622	-	700 x 19C
-	-	700 x 19
20-622	28 x 3/4	700 x 20C
22-622	28 x 7/8	700 x 22C
-	-	700 x 22
23-622	28 x 0.90	700 x 23C
-	28 x 7/8	-
24-622	-	700 x 24C
25-622	28 x 1.00	700 x 25C
-	28 x 1 1/16	-
26-622	-	700 x 26C
28-622	28 x 1.10	700 x 28C
-	28 x 1 5/8 x 1 1/8	-
30-622	28 x 1.20	700 x 30C
32-622	28 x 1.25	700 x 32C
-	28 x 1 5/8 x 1 1/4	-
33-622	28 x 1.30	700 x 33C
35-622	28 x 1.35	700 x 35C
37-622	28 x 1.40	700 x 35C
-	28 x 1 5/8 x 1 3/8	-
40-622	28 x 1.50	700 x 38C
-	28 x 1 5/8 x 1 1/2	-
42-622	28 x 1.60	700 x 40C
44-622	28 x 1.625	700 x 42C
47-622	28 x 1.75
50-622	28 x 2.00	-
-	29 x 2.00	-
-	28 x 1.90	-
55-622	28 x 2.15	-
-	29 x 2.15	-
60-622	28 x 2.35	-
-	29 x 2.35	-
32-635	28 x 1 1/2 x 1 1/8	770 x 28B
-	-	700 x 28B
-	-	700B Course
40-635	28 x 1 1/2	700 x 38B
-	28 x 1 1/2 x 1 5/8	700B Standard
44-635	28 x 1 5/8 x 1 1/2	700 x 42B
28-642	28 x 1 5/8 x 1 1/2	700 x 28A
37-624	28 x 1 3/8	700 x 35A

29"
ETRTO	INCHES	mm
50-622	29 x 2.00	-
52-622	29 x 2.00	-
-	28 x 2.00	-
54-622	29 x 2.10	-
-	28 x 2.10	-
55-622	29 x 2.15	-
-	28 x 2.15	-
55-622	29 x 2.25	-
58-622	29 x 2.35	-
61-622	29 x 2.40	-
-	28 x 2.35	-
75-622	29 x 3.00	-

Bicycle tires for different types of bikes

In our bike tire size chart, there are 3 columns, one for each measurement, which makes it easy to convert bike tires sizes from metric to imperial / or vice versa. You can also use the bike tire size chart to convert ETRTO (European Tire and Rim Technical Organisation) bicycle tire size data to one of the other types.This way you will find the correspondence between the measurement indicated on your tire and that indicated for the tire you wish to buy.

Typical Road bikes

For road bikes, bike tire sizes are generally expressed in metric measurements. Although road bicycle tire sizes can be expressed using the other systems, products like Michelin road racing tires are always listed with their 700mm diameter appearing first. This is also standard practice for racing tires, cyclocross tires, everyday road bike tires, training tires as well as road bike tires designed for harsher terrains – such as Michelin gravel tire.

Typical MTBs and city bicycles

However, it’s not the same for mountain bikes. An MTB tire will typically display primary tire dimensions in inches (Imperial measurement). This is the same for city bikes, a bicycle class which also includes trekking bikes as well as children's bicycles.

ETRTO is a common standard

ETRTO is a useful multi-purpose system designed to work well for all types of bicycles. So, anything from a child’s first bicycle to a professional road bike will have tire listings that use this system. But as said before, this type of measurement is the least used.

Can I change the tire size on my bike?

Perhaps you are wondering whether you can change bicycle tire sizes to suit different situations? It is sometimes possible to use different bike tire sizes, provided the difference in size is only negligible. For example, some MTB riders choose slightly wider tires on certain terrains.

However, the dimensions of your wheel rim will obviously remain the same, so it is usually best to stick to the recommended bike tire size. Otherwise your bike’s performance could be severely impaired, which could even interfere with the operation of the brakes. Your bike tire size depends on your bike specifications. So if you want to change your tire size, Michelin advises you to contact a certified professional or your bike manufacturer.

My new tire seems to be narrower, is this normal?

If your rim dates from before 2021, a 2021 or post-2021 tire may appear narrower when fitted, as today’s tire models are designed to reach their nominal width on wider rims, complying with the latest ETRTO standards, at the recommended operating pressure.

What impact on performance and safety?

No need to worry. A slightly narrower tire may simply alter your feeling of comfort. Michelin tires, which comply with the latest ETRTO standards, also maintain a high level of performance and safety on your pre-2021 rims.

The illustrated explanation

Read our Frequently Asked Questions.

Three different measurement systems are in common use, and not all tires display all three. ETRTO (the standardized European system) expresses size as two numbers — for example 25-622 — where the first is width in millimeters and the second is the rim's bead seat diameter in millimeters. Imperial sizing uses inches — for example 700 x 25C or 29 x 2.10. Metric sizing uses millimeters for both diameter and width — for example 700 x 25. The same physical tire may carry all three designations on its sidewall, which is more information than confusion once you know the system.

The ETRTO code — the most unambiguous tire size format — has two numbers separated by a dash. The first number is the tire's inflated width in millimeters. The second is the rim's bead seat diameter in millimeters. For example, 25-622 means 25mm wide on a 622mm bead seat diameter rim. The bead seat diameter is the critical compatibility number — a tire and rim must share the same bead seat diameter to fit correctly. Michelin follows ETRTO standards for all its bicycle tire sizing.

700c is an imperial metric designation commonly used for road bikes. The '700' refers to the approximate outer diameter of the inflated tire in millimeters; the 'c' was a historical designation for rim width that has become standardized to mean a 622mm bead seat diameter rim. All '700c' tires and rims share the 622mm bead seat diameter in ETRTO terms — they're compatible regardless of width variation (700 x 23, 700 x 25, 700 x 32 are all 622mm bead seat diameter tires that mount on the same rims).

Within limits, yes. The rim has a recommended range of compatible tire widths — a rim that's too narrow for a very wide tire won't support the tire's shape correctly, and a rim that's too wide for a narrow tire may cause the tire to seat poorly. The bike frame and fork also have maximum tire clearance — the maximum width before the tire contacts the frame. The ETRTO organization provides recommended rim-to-tire width ranges. Michelin's advice is that if you want to change tire size significantly, consult a bike professional or the bike manufacturer to confirm compatibility.

650b (ETRTO bead seat diameter 584mm) has become the standard for most current trail and enduro mountain bikes and is also used on many gravel bikes, where it's sometimes called 650b or 27.5-inch. On mountain bikes, 650b rims fit between the older 26-inch (559mm) and the 29-inch standard (622mm). On gravel bikes, 650b wheels allow the use of wider tires than a 700c wheel would fit in the same frame, which is why adventure and bikepacking-focused gravel bikes often use 650b.

Michelin provides a tire size conversion chart at michelinman.com that aligns all three sizing systems — ETRTO, imperial, and metric — so you can identify the equivalent sizes across systems. Find the size currently on your tire in one column and read across to find the corresponding designation in the other systems. This is useful when a replacement tire is listed in a different sizing format than your current tire but you want to confirm it's compatible. The bead seat diameter (the second number in ETRTO) is the most critical compatibility parameter.

Bike Tire Sizes explained: our complete guide

Where can you find your bike tire size?

Understanding bike tire sizes

ETRTO bicycle tire size measurements

Imperial bicycle tire size measurement

Metric bicycle tire size measurements

Bike tire size chart: How to convert a measurement?

‎ Bike tire size chart

12"

14"

16"

17"

18"

20"

22"

24"

26"

27"

27,5"

28"

29"

Bicycle tires for different types of bikes

Typical Road bikes

Typical MTBs and city bicycles

ETRTO is a common standard

Can I change the tire size on my bike?

My new tire seems to be narrower, is this normal?

What impact on performance and safety?

The illustrated explanation

BEFORE 2021

SINCE 2021

BEFORE VS NOW

FAQ

Related articles

How can bicycle rolling resistance affect your ride?

Technical glossary

Where can you find your bike tire size?

Understanding bike tire sizes

ETRTO bicycle tire size measurements

Imperial bicycle tire size measurement

Metric bicycle tire size measurements

Bike tire size chart: How to convert a measurement?

‎ Bike tire size chart

12"

14"

16"

17"

18"

20"

22"

24"

26"

27"

27,5"

28"

29"

Bicycle tires for different types of bikes

Typical Road bikes

Typical MTBs and city bicycles

ETRTO is a common standard

Can I change the tire size on my bike?

My new tire seems to be narrower, is this normal?

What impact on performance and safety?

The illustrated explanation

BEFORE 2021

SINCE 2021

BEFORE VS NOW

Why are bicycle tire sizes so confusing, and how many sizing systems exist?

How do I read an ETRTO tire size?

What does 700c mean in bicycle tire sizing?

Can I fit a wider tire on my current bike without changing wheels?

What is the 650b wheel standard and when is it used?

How do I use Michelin's tire size chart?

Related articles

How can bicycle rolling resistance affect your ride?

Technical glossary