Of course, you can always replace like with like, but if you want to try running a different tyre, or maybe just the same tyre in a different width, there are a few things to consider.<\/span><\/p>\n In this guide, we\u2019ll run <\/span>through everything you need to know about bike tyre sizes, and delve into the unique specifications of road, mountain, gravel and commuter bike tyre sizes.<\/span><\/p>\n Use the links below to jump to the section you need \u2013 or read on for our full in-depth guide.<\/p>\n There are two parameters that define bike tyre size:<\/p>\n The tyre diameter, or to be more specific the tyre bead diameter, is defined by the size of the wheel that it has to fit on. We\u2019ll cover this in more detail.<\/p>\n Tyre width is also a factor to consider. There are more options here, as well as some variability in the width the tyre ends up when it\u2019s mounted on your wheel rim. We\u2019ll come on to this.<\/p>\n Confusingly, there are multiple ways in which tyre and wheel sizes are designated.<\/p>\n Road bike tyres are typically sized using the traditional European measurement system. Usually, a road bike<\/a> will have 700c<\/a> rims and fit 700c tyres.<\/p>\n Mountain bikes<\/a>, on the other hand, usually have tyre and wheel sizes designated in inches, reflecting the US roots of the sport.<\/p>\n Typical mountain bike wheel sizes<\/a> and tyre sizes are 29in, 27.5in and, historically, 26in.<\/p>\n 29in wheels and tyres have the same bead diameter as 700c; 27.5in is the same diameter as 650b.<\/p>\n The 26in wheels that dominated mountain bikes for years are now more-or-less obsolete.<\/p>\n Like road bikes, gravel bikes<\/a> have metric-sized wheels, but they tend to be either 700c or 650b<\/a>.<\/p>\n It gets even more complex, because there\u2019s also an ETRTO sizing that\u2019s typically printed on the sidewalls of tyres, defined by the European Tyre and Rim Technical Organisation.<\/p>\n This is controlled by an ISO international standard and ensures that any tyre of a designated diameter should fit on any rim of the same designated diameter.<\/p>\n The ETRTO number is expressed in millimetres:<\/p>\n With this in mind, there are actually a limited number of wheel and tyre diameters readily commercially available. A tyre of a specified diameter should fit a rim of the same diameter, though, as we\u2019ll come on to, the width of the tyre and rim are also significant factors to consider.<\/p>\n Despite the ETRTO standards outlined above, manufacturing tolerances mean the fit between the tyre and rim can be tighter or looser than expected.<\/p>\n If you need to change a bike tyre<\/a> fitted with an inner tube<\/a>, that may just mean the difference between an easy job mounting a tyre and sore thumbs from prising an over-tight tyre onto a rim or off again.<\/p>\n For tubeless tyres<\/a>, it\u2019s more critical there\u2019s a close fit between the tyre and the rim, particularly for road bike tubeless tyres, where tyre pressures are higher and there\u2019s more risk of a blow-out than with an MTB or gravel bike tyre.<\/p>\n Manufacturers are now making the best tubeless road tyres<\/a> to much closer tolerances than a few years ago to ensure safety, particularly on the latest hookless rims<\/a>.<\/p>\n Makers of road bike wheels with hookless rims will often publish a list of tyres recommended for use with their wheels, and it\u2019s best to consult these lists to avoid any mishaps out on the road.<\/p>\n Although there are a limited number of tyre bead diameters to fit discrete wheel sizes, there\u2019s a lot more variation in tyre width.<\/p>\n To start with, mountain bike tyres are a lot wider than road bike tyres. This is one reason why you\u2019ll likely be unable to fit a mountain bike tyre in a road bike frame, although you can in principle fit a mountain bike tyre on a road bike rim.<\/p>\n Road and hybrid tyres are typically sized in millimetres, when it comes to width.<\/p>\n Most gravel bike tyres are also sized in millimetres, although super-wide gravel tyres \u2013 akin to mountain bike tyres \u2013 may be sized in inches.<\/p>\n Mountain bike tyres are typically sized in inches too.<\/p>\n The size of a tyre should be printed on its sidewall.<\/p>\n The definitive tyre size is the ETRTO number, which will be embossed on the sidewall of all tyres.<\/p>\n It consists of a tyre width measurement in millimetres, a dash and then the tyre bead diameter, also in millimetres. For example, 25-622 means the tyre is 25mm wide and will fit a 700c wheel, while 65-584 means the tyre is 65mm wide and will fit a 650b wheel.<\/p>\n Because ETRTO numbers are not commonly understood, most tyres will have a metric size such as 700c x 25mm, or an imperial size such as 27.5 x 2.60in embossed on them too, sometimes both.<\/p>\n It\u2019s often in black, and quite tricky to read, so outdoors or under a bright light is easiest to pick it out.<\/p>\n When it comes to choosing the best road bike tyres<\/a> for you, width is the key factor to consider.<\/p>\n Almost all road bike wheels are 700c (with a beam diameter of 622mm), although some bike brands fit 650b wheels (with a bead diameter of 584mm) to some of their smaller-sized bikes, so they can maintain a similar road bike geometry<\/a> to larger frame sizes.<\/p>\n In the past, 23mm was the typical width for most road tyres, and some tyres came in a 20mm width or narrower.<\/p>\n Now, 25mm is the narrowest tyre that typically comes fitted to road bikes and many bikes have 28mm tyres, with clearance on some of the latest bikes for 32mm rubber and beyond.<\/p>\nWhat defines the size of a bike tyre?<\/h2>\n
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<\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/picture><\/div>Tyre diameter and wheel diameter<\/h3>\n
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<\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/picture><\/div>What about ETRTO sizing?<\/h4>\n
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<\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/picture><\/div>Tyre width<\/h3>\n
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<\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/picture><\/div>How do I find the size of my current tyres?<\/h2>\n
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<\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/picture><\/div>Road bike tyre sizes explained<\/h2>\n
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