Calnago wrote:pdlpsher1 wrote:One has to keep in mind that the current crop of 23mm tires are really 25mm wide and would be labeled as 25mm a few years ago. The newer 25mm tires are really 28mm wide. So going back to a 23mm doesn't really say much about whether wider is good or bad.
I don't think that's true at all. The reason they measure out wider these days is because they are being mounted on wider rims. A 23mm tire will measure larger on a wider rim than it will on a narrower one (talking about clinchers only here, as tubulars are contained in their own casing and rim width doesn't affect them the same way). If you really want to see how big a 25mm clincher can get, just mount it on a new ENVE front rim. It won't clear a lot of road forks these days. The thing is, while there are variations between manufacturers I think the sizing is still based on the tires being mounted on "normal" rim with a 15mm internal width. Mount them in bigger rims and they expand accordingly.
Yes, clearance is becoming an issue across all bike manufactures and they are slowing the trend of wide rim. Caliper brake clearance is another issue. Envy made this http://enve.com/products/ses-4-5-ar specifically for disc.