before you buy a new tyre, you need to know the size first.
to do this look at your old tyre and choose the size customary to your country (see above list).
if this size indication can not be read, then look at the first size choice, for example 37-622.
the first number is the width of the tyre and the last number is the diameter.
you will also find this on the tyre: for example size 37-622 is 28x1 5/8x1 3/8;
the tyre is 37mm wide and has a diameter of 622mm
diameter 622mm x pi = 3.1415 gives the rim circumference -/- 1 to 2mm.
622x3.1414 = 1954 so as you can see, this is 1mm less than the rim circumference 1955.
if no size indication whatsoever can be found on your tyre, then look on the rim.
if the imprinted text on the rim is difficult to read, clean the rim and make sure there is enough light.
you will usually find two numbers on the rim:
- the width of the rim: take note that this is not the tyre width, as this is always wider than the rim.
- and the diameter of the rim.
example a: 18-622 is on the rim.
all tyres with the 3 digit number 622 fit on this rim, but you still do not know the width of the tyre yet.
normally you can use the following numbers as your starting point:
- if the rim width is 18mm, then the tyre width is 32mm
- if the rim width is 20 to 22mm, the tyre width is 37mm to 40mm.
if you are unable to work it out yourself, then consult your bicycle dealer.
we wish you lots of cycling pleasure.
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