On the other hand it increases the stress on the sidewall of the tyre. Mountain bike tyres are designed to take this extra stress but road tyres are not. Bigger tyres naturally require bigger inner tubes. On the left is a 700×32-47C inner tube, while the right is a 700×18-28C. Simon Bromley/Immediate Media

Finance is subject to application, financial circumstances and borrowing history. Performance Cycling Limited FRN: 720557 trading as Tredz are authorised and regulated by the Financial Conduct Authority. We are a credit broker not a lender – credit is subject to status and affordability and is provided by Mitsubishi HC Capital UK PLC. Terms & Conditions Apply. The initial two-digit number is the tyre section and roughly indicates the tyre width. Its actual width is normally less, but varies according to how the tyre is designed and the width of rim to which it is fitted. But the height of the tyre usually corresponds quite closely to tyre section, so overall diameter approximately equals the bead diameter plus twice the section. The former are simpler to use, but add a dead space above the valve, making inflation harder, while with the latter you need to make sure that there’s a fully airtight seal to the inner tube’s valve stem, or your tube will leak air. The ideal relationship between tyre and rim section is about 1.8 to 1, but any tyre from 1.4 to 2.2 times should fit – always provided that the bead diameters correspond. Some rims are also now marked according to ISO with their bead diameter and internal section (width where the tyre fits); 622-17 for the size usually fitted to touring and hybrid bikes, for instance. But some manufacturers give the overall width instead. Subtract 6mm from overall width to estimate the rim section, or simply measure the distance between the flanges.

You must make sure you replace your inner tubes with a tube that is the right size according to the diameter and width for your tyre. The size is almost always written somewhere on the sidewall of the tyre. Inner tubes typically state a wheel diameter and width range for which they will work, e.g. 26 x 1.95-2.125", indicating that the tube is intended to fit a 26 inch tyre with a width of between 1.95 inches and 2.125 inches. Valve extenders come in a range of sizes, types and even colours. These ones simply screw over the top of an open Presta valve, but you can also get ones that allow you to place the valve core at the top. Simon Bromley/Immediate Media Nowadays almost all rims have hooked flanges (required to retain folding tyres) that will hang onto tyres up to three times their width. This increases the cushioning effect: you get more comfort out of the same tyre at the same pressure when you fit it to a narrow rim – yet it still rolls just as easily. Another reason not to exceed the 2.2 limit on road is that a more bulbous tyre can deflect side ways with a noticeable effect on control and road holding. Conversely, fitting a tyre of less than 1.4 times the rim section will result in a harsh ride and more rolling drag than a larger tyre at the same pressure. Tubeless tyres the first is the width of the tire in millimeters and the second is the diameter of the tire in millimeters.

The Dunlop valve, also known as a Woods is a variation of pneumatic valve that is rarely used on modern bikes. However they were once popular. They look like a cross between the two valves, with a wider lower section, like the Schrader, then a collar and a narrow top section, like the Presta. As the rim drilling is the same for both Woods and Schrader, it is easy to replace the older tubes with the more modern variety. How can I choose the right valve length? Tubeless tyres, as the name suggests, do away with an inner tube and, in its absence, are reliant on the shape and tightness of the tyre bead to ensure the tyre doesn’t blow off the rim at high inflation pressures; in a conventional clincher tyre, the inner tube keeps the bead securely located under the rim hook.That’s how the diameter and circumference (circ – equals distance rolled in one turn of the wheel) are calculated in the Tyre size table. These figures are useful for setting your cycle-computer and precisely calculating gears. It ‘ll come as no surprise that there are bicycle tires in many different forms. There are big differences in pattern, size and above target. You can buy everything from studded tires and tires for BMX bikes to regular tires with a different pattern for adult and children’s bikes.

It is also possible to find a table of which corresponds to the tire air pressure, and an approximate weight of each bicycle tires. This may largely be a great advantage if, among other things need bicycle tires for a more professional needs or level. Often you can also find a table that says something about a price range for the selected bicycle tires. If you are facing and should change the tires on your bike, it is important that you choose the right bicycle tire sizes for your bike wheels. Each tire size is very variable depending on the type of bicycle tire you want, and depending on what type of bike you have. In this article you will get a small guide on how to choose the right bicycle tire size for your bike. Table of bicycle tires sizes Even worse, the same or very similar markings can sometimes be found on completely different sizes of tyre: 26×1½ and 26x1.5. It might be supposed that these two tyres are both notionally 26" diameter and one and a half inches in width, but 26×1½ is a whole inch bigger than 26×1.5.

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The former is ‘fractional’, the latter ‘decimal’, and as a rule decimal and fractional tyre sizes that look the same are not. Inner tubes are normally made of butyl rubber or Latex, they sit inside your tyre and are inflated with a pump, they sometimes puncture but are easily replaced. Inner tubes are simple but essential – unless you’re riding with tubeless tyres, you’ll always need an inner tube. Carrying spares is always a good idea, even if you are running tubeless, as a large slash or hole will not seal easily. Tubular tyres require skilled fitting; if unsure, consult a suitably trained cycle mechanic. Other sizes including 26" may be encountered; these are rare and it is advisable to make a direct match with a rim before buying. Recommended pressures

On the other hand, they’re much more fragile and more awkward to fit as they’re floppier than butyl tubes. Sometimes you can’t find any ISO size on a tyre, only the old-school markings. Although they’re familiar they can be confusing. Tyres of the same size may come with lots of different markings: 28×1¼×15/8, 28×1¾×1¼ or 700×32C, for example, which are all 32-622. There is no industry-wide convention for tubeless tyre fitment and satisfactory results are mostly likely using parts made for use together such as Mavic’s UTS (Universal Tubeless System) tyres and rims. Nevertheless, tubeless-compatible tyres are generally available in the standard 29"/700C/622mmISO, 27.5"/650B/585mmISO and 26"/559mmISO formats. It is inadvisable to use non-tubeless tyres without an inner tube as there is a risk of tyre blow-off. Tubular tyres One way to define it, popular in times past, was to measure the tyre’s outside diameter and its maximum width when inflated, but this can be misleading. For example, some tyres marked 28" are actually much less than 27 inches in diameter, while 26×1.5 and 26×1½ are two completely different sizes. Please Note: any reference to 'Royal Mail 24 ™' and 'Royal Mail 48 ™' are Official Royal Mail Service names and should not be interpreted as '24 Hour Delivery' and '48 Hour Delivery'.Home> Buying Guide: Inner Tubes Our Guide to Buying: Inner Tubes What are Cycling Inner Tubes? In a nutshell