Tire Sizes
What do the various size markings on bicycle tires mean?
Nowadays, bicycle tire sizes are all marked according to ETRTO (European Tire and Rim Technical Organization) standard. However, older English and French tire size dimensions are still used as well. The ETRTO size specification 37622 indicates the width of 37 mm and the tire inner diameter of 622 mm. This dimension is clear and allows a precise classification of the rim size. The inch marking (e.g. 28 x 1.40) states the approximate outer diameter (28 inches) and the tire width (1.40 inches). Another inch marking is 28 x 1 5/8 x 1 3/8 (approximate outer diameter x tire height x tire width); it is also common. Inch sizes are not precise and lack accuracy. For example, diameters 559 mm (MTB), 571 mm (Triathlon) and 590 mm (Touring) are all classified as 26 inch. Tires with diameters 622 mm and 635 mm are both classified as 28 inch. Oddly enough, tires with an inner diameter of 630 mm are classified as 27 inch. These classifications originate from the time of tire brakes. In those days, the exact outer diameter of the tire was defined by the brake. Depending on tire width, various standards for the inner diameter applied. Inch dimensions are widely used in both MTB sport and English language countries. Therefore, we will continue to use these specifications for all tires. But only in decimal form, e.g. 26 x 2.25. Experience tells us that nowadays very few users are familiar with the classical fractional inch dimensions, such as 28 x 1 5/8 x 1 3/8. When the 29 inch MTB tire size was introduced a few years ago, it had the same inner diameter of 622 mm, known as 28 inch in Europe. The latest tire size is 27.5 inches. This tire size is favored for MTBs which are too small for the very big 29 inch wheels, in order to benefit from the advantages of bigger diameters. This is the case, for example, with bicycles having a very long suspension travel or very small frame sizes. 27.5 inch tires have an inner diameter of 584 mm and are identical with the old French size marking 650B. French size markings (e.g. 700 x 35C) give the approximate tire outer diameter (700 mm) and width (35 mm). The letter at the end indicates the inner diameter of the tire. In this case, C stands for 622 mm. French size markings are not used for all tire sizes, so, for example, it is not used for MTB sizes. 
Size Designations Overview
ETRTO  Inch  French  
Size designation  37622 
28 x 1.40" 28 x 1 5/8 x 1 3/8" 
700x35c 
Outer diameter    Approx. 28"  Approx. 700mm 
Inner diameter  622 mm     
Tire section width  Approx. 37 mm 
Approx. 1.40" Approx. 1 3/8" 
Approx. 35 mm 
Tire section height    Approx. 1 5/8"   
How many tire sizes are there?
The following list shows all common tire sizes. For virtually every tire size, you should be able to find a corresponding ETRTOsize in this list.
The current Schwalbe sizes and markings are given in bold. We have tried to list in addition all tire sizes which are currently used on the market or which were used in the past. These classical fractional size indications are also often engraved on old Schwalbe tires. Sometimes, you still find them on current models which have already been available for quite a long time.
ETRTO  Inch  French  
7"  4793  7 x 1 3/4  
8"  4794 
20 x 4750 8 x 2 

5094  200 x 50  
54110  8 x 2 1/8 8 1/2 x 2  
32137  8 x 1 1/4  
10"  54152 44194  10 x 2 10 x 1 5/8  
11"  47222  11 x 13/4  
12"  47203  12 1/2 x 1.75 12 1/2 x 1.90  
54203  12 x 1.95  
57203  12 1/2 x 2 1/4 R  
62203  12 1/2 x 2 1/4  
32239  12 1/2 x 1 3/8 x 1 1/4  300 x 32A  
57239  12 1/2 x 2 1/4  300 x 55A  
14"  57251  14 1/2 x 2 1/4  300 x 55A 
47254  14 x 1.75 14 x 1.90  
40279  14 x 11/2  350 x 38B  
37288  14 x 1 5/8 x 1 3/8  350A 350A 350A Confort 350A Ballon 350A 1/2Ballon 350 x 32A  
40288  14 x 1 5/8  350 x 38A  
44288  14 x 1 5/8 x 1 3/8  350A 350 x 42A  
32298  14 x 1 1/4  350A 350 x 32A  
16"  40305  16 x 1.50  
47305  16 x 1.75 16 x 1.90  
54305  16 x 1.95 16 x 2.00  
57305  16 x 2.125  
40330  16 x 1 1/2  400 x 38B  
28340  400 x 30A  
32340  16 x 1 3/8 x 1 1/4  400A 400 x 32A  
37340  16 x 1 3/8 x 1 1/4  400 x 35A 400A Confort 400A Ballon 400A 1/2 Ballon  
44340  16 x 1 5/8  
28349  16 x 11/8  
32349  16 x 11/4 NL  
37349  16 x 1 3/8  
17"  32357  17 x 1 1/4  
37369  17 x 1 1/4  
18"  28355  18 x 1 1/8  
40355  18 x 1.50  
47355  18 x 1.75 18 x 1.90  
37387  18 x 1 3/8  
40387  18 x 1 1/2  
28390  18 x 1 1/8  450 x 28A 450A  
37390  18 x 1 3/8  450 x 35A 450A 450A Confort 450A Ballon 450A 1/2Ballon  
55390  450 x 55A  
57390  450 x 55A 450A  
37400  18 x 1 3/8  
20"  54400  20 x 2 x 1 3/4 20 x 2F4J  
28406  20 x 1 1/8  
32406  20 x 1.25  
35406  20 x 1.35  
37406  20 x 1 3/8  
40406  20 x 1.50  
44406  20 x 1.625  
47406  20 x 1.75 20 x 1.90  
50406  20 x 2.00  
54406  20 x 2.00  
57406  20 x 2.125  
54428  20 x 2.00  
40432  20 x 1 1/2  
37438  20 x 1 3/8  500A  
40438  20 x 1 3/8  500 x 38A  
28440  500 x 28A 500A 500A Standard  
40440  20 x 1 1/2NL  500 x 38A  
28451  20 x 1 1/8  
37451  20 x 1 3/8 B.S.  
22"  44484  22 x 15/8 x 11/2  
25489  22 x 1.00  
37489  22 x 1 3/8 NL  
40489  22 x 1 3/8 x 1 1/2  
50489  22 x 2.00  
28490  550 x 28A 550A 550A Standard  
32490  22 x 1 3/8 x 1 1/4  550 x 32A 550A  
37490  22 x 13/8  550 x 35A 550A Confort 550A Ballon 550A 1/2 Ballon  
37498  22 x 1 3/8 x 1 1/4  
32501  22 x 1 1/4  
37501  22 x 1 3/8  
24"  40507  24 x 1.50  
44507  24 x 1.625 24 x 1.75  
47507  24 x 1.75 24 x 1.85/1.90  
49507  24 x 1.85  
50507  24 x 1.90/2.00 24 x 2.00 24 x 2.125  
54507  24 x 2.10  
57507  24 x 2.125 24 x 2.00  
60507  24 x 2.35  
44531  24 x 1 5/8 x 1 1/2  
40534  24 x 1 1/2  
25540  24 x 1.00  
32540  24 x 1 3/8 x 1 1/4 24 x 1 3/8  
37540  24 x 1 3/8  
40540  24 x 1 3/8 x 1 1/2  
22541  
25541  600 x 25A  
28541  600 x 28A 600A 600A Standard  
32541  24 x 1 3/8 x 1 1/4 N4  600 x 32A  
37541  600 x 35A 600A Confort 600A Ballon 600A 1/2 Ballon  
26"  25559  26 x 1.00  
35559  26 x 1.35  
37559  26 x 1 5/8 x 1 3/8 26 x 1.40  
40559  26 x 1.50  
44559  26 x 1.625 26 x 1.50/1.75  
47559  26 x 1.75 26 x 1.85/1.90  
50559  26 x 1.90 26 x 1.95 26 x 1.90/2.00 26 x 2.00/2.10  
54559  26 x 1.95 26 x 2.10 26 x 2.125  
57559  26 x 2.125 26 x 2.20/2.25  
60559  26 x 2.35  
62559  26 x 2.50  
20571  26 x 3/4  650 x 20C  
23571  26 x 7/8  650 x 22C  
40571  26 x 1 1/2 CS 26 x 1 3/8 x 1 1/2 NL 26 x 1 5/8 x 1 1/2  650 x 35C 650 x 38C  
47571  26 x 1 3/4 650 CS confort  650 x 45C  
54571  26 x 2 x 1 3/4  650 x 50C  
28584  26 x 1 1/8 x 1 1/2  650 x 28B  
32584  650 x 32B  
35584  26 x 1 3/8 x 1 1/2  650 x 35B 650B Standard  
37584  26 x 1 1/2 x 1 3/8 26 x 1 1/2  650 x 35B  
40584  26 x 1 5/8 x 1 1/2  650 x 42B 650B SemiConfort 650B 1/2 Ballon  
20590  650 x 20A  
25590  26 x 1 1/8, 1 1/4 26 x 1 3/8  1 1/4  650 x 32A  
28590  26 x 1 1/8  650 x 28A  
32590  26 x 1 1/4 26 x 1 3/8 x1 1/4  650 x 32A  
35590  26 x 1 3/8  650 x 35A  
37590  26 x 1 3/8  650 x 35A 650A  
40590  26 x 1.50 28 x 1 3/8 x 1 1/2  650 x 38A  
44590  
32597  26 x 1 1/4  
27"  40609  27 x 1 1/2  
20630  27 x 3/4  
22630  27 x 7/8  
25630  27 x 1.00 27 x 1 1/16  
28630  27 x 1 1/8 27 x 1 1/4 Fifty 27 x 1 1/4  
32630  27 x 1 1/4  
28/32630  27 x 1 1/4  
35630  27 x 1 3/8  
28"  18622  28 x 3/4  700 x 18C 
19622  700 x 19C  
20622  28 x 3/4  700 x 20C  
22622  28 x 7/8  700 x 22C  
23622  28 x 7/8  700 x 23C  
25622  28 x 1.00  700 x 25C  
28622  28 x 1.10  700 x 28C  
30622  28 x 1.20  700 x 30C  
32622  28 x 1.25  700 x 32C 700C COURSE  
35622  28 x 1.35  700 x 35C  
37622  28 x 1.40  700 x 35C  
40622  28 x 1.50  700 x 38C  
42622  28 x 1.60  700 x 40C  
44622  28 x 1.625  700 x 42C  
47622  28 x 1.75  700 x 45C  
50622  28 x 1.90, 28 x 2.00  
60622  28 x 2.35  
32635  28 x 1 1/2 x 1 1/8  770 x 28B 700 x 28B 770B COURSE  
40635  28 x 1 1/2 28 x 1 1/2 x 1 3/8  700 x 38B 700 x 35B 700 Standard 700B Standard  
44635  28 x 1 5/8 x 1 1/2  700 x 40/42B  
28642  28 x 1 3/8 x 1 1/8  700 x 28A  
37642  28 x 1 3/8  700 x 35A 
What is actually the difference between 28 and 29 inches?
The silliest answer to this question would be to say that the difference is exactly 1 inch. Another answer would be: There is no difference. Both tire sizes have the same inner diameter of 622 mm and can therefore be fitted on the same rims. In Europe, 28 inches is a traditional size for touring bicycles. In many countries it is even the most frequent tire size used. In countries outside Europe the rim diameter of 622 mm is only rarely used. Bicycle travelers who want to buy spare tires for a 28inch touring bicycle anywhere in the world, can tell you a thing or two about it. A few years ago 29 inch tires were introduced as a new wheel size for mountain bikes in the US. The marking was created, as the MTB tires are more voluminous and the outer diameter measures approximately 29 inches.
Both indications are, however, very imprecise. A less wide 28 inch tire, e.g. with a tire width of 23 mm, which is usual for a road bike, has in fact only an outer diameter of something more like 26 inches. In the case of a tire width of 40 mm, 
What are the advantages of the new wheel sizes 27.5 and 29 inches?
The new sizes are well established on the market and this is for good reason. The advantages of the large wheels outweigh the disadvantages. 29 inch wheels weigh a little more, are less maneuverable and possibly less stiff, but they roll clearly There are, however, some bicycles which do not have enough clearance for a large 29 inch wheel, e.g. in the case of very small frame sizes and in particular bicycles with very long suspension travel. This is where the new wheel size 27.5 comes in. Schwalbe will continue to offer all usual MTB tires for all three diameters. 