Plow13

i currently use 700x25 tire and i was wondering if it a big difference going to 700x23? what are pros and cons of using a 25 vs 23?

666

I think the short answer is "no". The actual width of tires can vary substantially from the stated size. Rolling resistance varies widely across brands/models. 10 years ago when I was racing everyone ran 18s or 20s. Now, everyone is running 23s. There are many, many tires out there to chose from. Check out the info on Sheldon Browne's site or ask WaterRockets PhDs for a copy of one of his dissertations.

barba

I wouldn't do it if there is any life left in your current tires. Once you wear your 25s out, try a set of 23s and see what you think. My guess is that you won't be able to feel much of a difference.

Road Kill

I went from 25's to 23's on my Trek and could just tell a slight difference. I prefer the 23's.

johnny99

You can and should run a wider tire at a lower air pressure than a narrower tire. The lower pressure will give you a plusher ride.

Retro Grouch 

It's only 2mm! How much difference can there be?

In theory the wider tire will allow you to run slightly lower air pressure without pinch flatting. The narrower tire, having less frontal area, will be more aero. In real life you'll probably run about the same air pressure in either one and as to the frontal area, it's only 2mm wider. How much difference can there be?

johnny99

Run the wider tire at a 10psi lower pressure. Your butt will feel the difference.

stapfam

I went from a 26 Kenda to a 23 Michelin and there was a difference. Not only the width but the quality of the tyre you get will make a difference.