Tire Dimensions

 


 

What is the exact circumference of my tire?

In order to accurately program a bicycle computer, it is generally necessary to enter the exact tire circumference.

The tire circumference varies depending on the rim, the inflation pressure and the load on the tire. For these reasons, it is not possible to list an exact tire circumference. In order to accurately program a bicycle computer, we recommend a simple rolling test with the rider on the bicycle.

The approximate tire circumferences for the most common sizes are listed in the table below.

 

Inch ETRTO Approximate Tire
circumference

16"

50-305 1265 mm
  35-349 1315 mm
  37-349 1330 mm

18"

40-355 1380 mm
  50-355 1440 mm

20"

23-406 1420 mm
  28-406 1450 mm
  35-406 1510 mm
  40-406 1540 mm
  47-406 1580 mm
  50-406 1600 mm
  54-406 1620 mm

24"

47-507 1900 mm
  50-507 1910 mm
  54-507 1930 mm

24"

57-507 1955 mm
  60-507 1980 mm

26"

35-559 1990 mm
  40-559 2030 mm
  47-559 2050 mm
  50-559 2075 mm
  54-559 2100 mm
  57-559 2120 mm
  60-559 2160 mm
  37-590 2100 mm
Inch ETRTO Approximate Tire
circumference

27"

32-630 2200 mm

27,5"

54-584 2195 mm
  57-584 2215 mm
  60-584 2240 mm

28"

20-622 2100 mm

28"

23-622 2125 mm
  25-622 2135 mm
  28-622 2150 mm
  30-622 2160 mm
  32-622 2170 mm
  35-622 2185 mm
  37-622 2200 mm
  40-622 2220 mm
  42-622 2230 mm
  47-622 2250 mm
  50-622 2280 mm
  40-635 2250 mm

29"

54-622 2310 mm
  57-622 2330 mm
  60-622 2340 mm

 


 

 

Why are tires often narrower than the stated tire size?

In order to ensure that tires have sufficient frame clearance, tire manufacturers generally prefer to keep production closer to the lower end of the permitted tolerance (+/- 3 mm).

Carcass casing materials have become more and more sophisticated over time. That reduces the tire widening after the fitting.

Furthermore, inflation pressure also plays a major role. With maximum inflation pressure the tire becomes wider than with low pressure. And a recently fitted tire still widens over time. This can make a difference of 1 to 2 mm.

The tire width is measured at the widest point, i.e. outside the lug.

 


 

 

Will the tire fit into my frame?

The question whether tires will fit into a particular frame is often asked in relation to our ultra-wide tires.

Please bear in mind that with the large number of different bicycle models it is impossible to check the compatibility of all frames and tires.

The following list shows the exact diameters and widths of our ultra wide tires. This should allow you to identify if there is sufficient frame clearance for the selected tire.

 

Inch Tire
Maximum width
(A)
Maximum diameter
(B)
Diameter at maximum width
(C)
20"
Big Apple
60-406
60 mm
529 mm
469 mm
26"
Al Mighty
60-559
60 mm
684 mm
670 mm
 
Al Mighty
60-559
65 mm
693 mm
673 mm
 
Big Apple
60-559
60 mm
683 mm
616 mm
 
Big Betty
62-559
61 mm
690 mm
668 mm
 
Crazy Bob
60-559
61 mm
681 mm
625 mm
 
Fat Albert
60-559
59 mm
688 mm
664 mm
 
Fat Frank
60-559
60 mm
690 mm
664 mm
 

Racing Ralph
62-559

59 mm
687 mm
660 mm
 
Space
60-559
59 mm
682 mm
677 mm
29"
Big Apple
50-622
49 mm
727 mm
676 mm
 
Big Apple
60-622
60 mm
745 mm
678 mm
 
Little Albert
54-622
56 mm
741 mm
735 mm
 
Marathon Supreme
50-622
49 mm
725 mm
676 mm
 
Marathon XR
50-622
49 mm
725 mm
701 mm

 


 

Which tire fits which rim?

The inner diameter of the tire must match the rim bead seat diameter. For instance, a tire size 37-622 fits on a 622 x 19C rim.

Furthermore, the tire width must match the rim width. The following table shows possible combinations of tire widths and rim widths according to ETRTO.

There are many additional combinations which are not listed in this table, but nevertheless, work out in practice very well. It goes without saying that you ride with these combinations at your own risk. Unfortunately, the ETRTO standard in reality often lags behind. For example, very wide rims become more and more popular these days. The usage of wider rims also makes sense, because they support the tire’s stability. You can reduce the inflation pressure, before the riding behavior becomes spongy.

 

 

Possible combinations of tire width and rim width (crotchet type rim) according to the ETRTO

 

 
Tire section width
Rim width
(mm)
18
20
23
25
28
32
35
37
40
44
47
50
54
57
60
62
13c
x
x
x
x
 
 
 
 
 
 
 
 
 
 
 
 
15c
 
 
x
x
x
x
 
 
 
 
 
 
 
 
 
 
17c
 
 
 
x
x
x
x
x
x
x
x
x
 
 
 
 
19c
 
 
 
 
x
x
x
x
x
x
x
x
x
x
x
x
21c
 
 
 
 
 
 
x
x
x
x
x
x
x
x
x
x
23c
 
 
 
 
 
 
 
x
x
x
x
x
x
x
x
x
25c
 
 
 
 
 
 
 
 
 
x
x
x
x
x
x
x
27c
 
 
 
 
 
 
 
 
 
 
x
x
x
x
x
x
29c
 
 
 
 
 
 
 
 
 
 
 
 
x
x
x
x