23 or 25 mm?

[Valv.Piti]

Gonna buy some new Continental GP 4000 S II (should be the best on the market, pretty much), but Im unsure whether to buy them as 23 or 25 mm. I don't really know that much about it.

Pros and cons?

 

[King Boonen]

what kind of riding are you doing? Just general riding about? Road racing? TTs? I won't ride anything below a 25 these days.

 

[Jspear]

I use 25...never used 23 so I can't say anything negative. That's the exact tire I use. I like them a lot. Decent puncture resistance. Pretty fast. I can average between 3,000 and 4,000 miles a tire.

 

[Cookster15]

I moved to 25s when I picked up my brand new race bike a year ago - Schwalbe 1's . I was initially sceptical having ridden through the 90s on 19mm Continental Tubular race tyres (Triathlon and road racing) and on 22s or 23's since the 2000's (road racing).

But 25s do everything people say, ride slightly lower pressure, better ride, more grip. The biggest difference is descending where the extra grip and added confidence is most noticeable, seems like you have an added margin for error and don't feel on the limit. A friend of mine runs 25 Contis and showed me he was wearing out the sidewall logo as he had the confidence to lean further into corners!

 

[Mwburton]

I use both. On some of my bikes I use a 23 on the front and a 25 on the back. Different rim widths create a different tire profile and a 23 on one rim could be very close to a 25 on another rim. Many of my friends starting moving to larger volume tires when it started being "the thing to do" but they had skinny little rims and their tire/ wheel profile looked like a light bulb. That isn't good for aerodynamics or great cornering in my opinion.
If I were in your situation I would start with 25's and see how they fit, turn, ride and then adjust from there.

 

[DFA123]

Another vote for 25mm here - for comfort if nothing else. One thing to make sure though is that they will fit on your bike. Continental GPs come up quite big and, if you have fairly wide rims, it's possible on some models that you could get some rubbing on the chainstays with 25mm - especially when putting out high power. This is more of an issue with slightly older models with aggressive racing geometry (IIRC Cannondales were one brand with a few issues) - most models from the last couple of years should be fine, with 25s now coming pretty much as standard.