# How to measure the size of a suitable tire for my bike?

If I have the diameter of the rim of my bike and also have the width o this rim, how can I determine which tire is good for me?

• possible duplicate of How are tire sizes measured? Commented Nov 27, 2014 at 0:05
• If there's a tire on the rim, read the numbers off of it. Commented Nov 27, 2014 at 14:15

Measure the diameter of the bead seat (i.e. the place where the tire bead will sit). It will most likely be one of these:

• 559mm = MTB 26 inch tire.
• 622mm = 700C (a.k.a 29er)
• 630mm = 27 inch that is old enough to remember the Bee Gees.

If it's not one of those, look it up here: http://sheldonbrown.com/tire-sizing.html#iso

The new tire will have a marking on it like 28-622. That second number is the diameter.

• Also 650b (584 mm) is making a comeback. Commented Nov 26, 2014 at 22:39
• 28-622 the first number is the width in mm! Commented Nov 27, 2014 at 8:40
• But note that the tire width is greater than the rim width. Commented Nov 27, 2014 at 14:16