I have a hybrid Dawes, about 25 years old. I think it's currently got 700x35mm. I would like to fit thinner tires but how do I know if the rims will accept them. Is there a way to know?

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    How wide are the rims? If, measured inside between the flanges, the rims are no wider than about 20mm then they should handle 25mm tires. – Daniel R Hicks Jul 28 '18 at 12:28
  • @DanielRHicks some of the modern rims are 21mm or even 23mm ID and work with 25mm (claimed) tires just fine. The tire will grow wider, exactly how much depends on manufacturer, but it might become as wide as 30mm. I see no reason why older rims would change anything, so I'd say your estimate is on a safe side. – Klaster_1 Jul 28 '18 at 12:59
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    Why do you want thinner tyres? What advantage to you expect ? Or is it a matter of availability ? – Criggie Jul 29 '18 at 10:01
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    There is some discussion about up to which point narrow tires are actually faster. Recently the trend is towards wider rims and tires. 25mm tires on rims with ~18mm inner width seems to be the new norm on road bikes. 28mm is now also often used on training road bikes. The tire model itself will have much more impact than the width. – Michael Jul 29 '18 at 16:38
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    I currently have 35mm. So that assume 25 or 28 with slicker treads will be faster even if 1 to 2 mph. – user7668482 Jul 30 '18 at 10:56

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