Understanding road bike tyre sizes?

chris_king

Just shopping about for new tyres for my Bianchi, as I dont like the Vittoria's currently fitted. My current tyre size is 700x25. I'm looking about and most seem to be advertised as 700x23 or 700x20. I'm guessing (not assuming, we know where that leads!) that 700 is the diameter and 20, 23, and 25 are the widths of the tyre? Any advantages/disadvantages to me going to a 700x23?

Cheers,

Chris.

night_porter

By having 2mm less width all the way around the tyre you have less air this means that you will feel that it is a harder ride because the tyre is unable to compress or deflect as much.

However, on the upside less rubber in contact with the road should mean less rolling resistance and you should be able to go faster for a given effort.

Of course this will only reflect if you are using the exact same make/model of tyres because it is possible to buy very fast 25mm tyres and very soft 23mm tyres.

As with everything you pay your money and you get your choice.

STEFANOS4784

continental gp4000s 700x23 is all you need to know

Manufacturers lie sometimes as well, from what i gather, so don't worry too much.

People will say "25 are much more comfortable" or "23 roll much better" in reality the differences are marginal IMO.

sungod

unless you are riding smoooooooooth roads i wouldn't go below 23

i use gp4000s 23mm, it's not so comfy on rougher road surfaces - rolling resistance can go much higher than a fatter tyre in that situation - very grippy, but they do seem to cut up more in wet weather

tbh 25 or 28 might be better, depends what type of riding you are doing

watch out for drain covers, cable slots, cracks in the road etc., the narrower the tyre the more these can affect you

sheldon brown on tyre sizing...

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

chris_king

Cheers all. Shall do some shopping tonight. I'm doing around 50 miles a week, and doing a BHF charity ride in October which is 55 miles, so will see what will suit my riding best.