# Tyre sizes

Discussion in 'Bicycle Mechanics and Repairs' started by Dave5N, 27 Apr 2008.

1. ### Dave5NÜber Member

Could someone please directme to a chart of absolute tyre sizes? Eg, what is the inflated circumference of a 700x23 tyre?

2. OP

### Dave5NÜber Member

Think I have worked it out now - the tyre size plus twice the width?

3. ### fecklessÜber Member

Location:
Not all that close
Unsurprisingly, Sheldon has a moderately definitive article on tyre sizing.

http://www.sheldonbrown.com/tire-sizing.html

Doesn't contain anything about the rolling diameters, though I'm not sure you could have a definitive rolling diameter for any size of tyre as it'll vary according to make.

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4. ### hubgearfreakÜber Member

yes. 622 + (2x23) = 668

but as feckless says, it'd depend on the make, so whilst the above will be close, is close, close enough?

5. OP

### Dave5NÜber Member

That's the problem. AT the moment I am not quite inside three centimetres. Not a lot of leeway.

6. ### hubgearfreakÜber Member

i don't understand, sorry

7. ### Jacomus-rides-GenNew Member

Location:
Guildford / London
Why dont you just put a spot of ink on the trye, roll it one revolution and then measure the distance between the two spots of ink??

Best to do this on the kitchen floor when the missus is out and have the ink wiped off before she returns.

Location:
Kent
You have to take account of the fact the tyre goes down a bit when you ride it, under the weight of the rider.

9. ### briankNew Member

So you sit on the bike, one hand on the worktop/wall, and roll forward one turn of the wheel.

10. OP

### Dave5NÜber Member

I was trying to get as close to gear restriction as possible. Short of buying rings and sprockets in diffferent sizes and trying them, I was doing the maths first to see what would work.