Inner tube 3.50-8 for wheelbarrow tyre 8" Potreba

Product Information

This method is becoming obsolete, but you may still have tyres marked in this way. Measurements can be in inches or millimetres (look at the examples above, it's fairly obvious which is which). The first part is the overall tyre height, the second is the tyre width. Valves come in different shapes & sizes to accommodate a wide variety of applications & wheel rim configurations. There are four main categories that inner tube valves fall into & within each are a handful of popular valve models to choose from: This method is widely used on turf and ATV tyres and is probably the easiest to understand. The first part is the overall height (from the ground to the top of the tyre) of the tyre in inches, the second part is the width of the tyre in inches, and the third part is the rim diameter in inches.

The rim diameter is not mentioned in this size marking, but it can be easily worked out, because the tyre sidewall height will be the same as the tyre width. So, an 18x4 tyre is 18" tall, 4" wide, and fits a 10" diameter rim (18" overall height minus two lots of 4" high sidewalls). The modern equivalent size for an 18x4 would therefore be 4.00-10. 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 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. There are several methods for giving the size of tyres, with measurements sometimes in inches, sometimes in millimetres, sometim es in both! To help you understand a little better, we have examples and explanations of each method below, from which you should hopefully be able to recognise your own size markings.

Measuring Advice

Butyl rubber is the industry standard for common replacement inner tubes, offering a relatively cheap and readily available replacement product. Butyl is strong and resistant, and there are lightweight versions for those looking for weight savings - the Specialized Turbo range and Continental Supersonic tubes are popular versions. What are the differences between Latex and Butyl rubber tubes?

As already mentioned, it is important not to mix tyre sizes or types on motorised machinery as there can be significant variation in heights and widths between different manufacturers. We have even found that sometimes tyres of exactly the same size marking can vary significantly. As with car tyres, we would suggest you replace your tyres in pairs to ensure optimum performance. 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.

Common inner tube 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'. Originally, tyres were marked with the exact number of canvas layers (plies) built into the tyre. This was an indication of the strength of that particular size of tyre. It's fairly obvious that a 4 ply wheelbarrow tyre will have a different load capacity to a 4 ply car tyre. As stronger materials were developed, the number of layers could be reduced whilst still maintaining the same strength in the tyre. The designation Ply Rating therefore does not indicate the actual number of layers or plies in the tyre, but the number of layers originally required to give the desired load capacity. When working with PR marked tyres, you must use the actual manufacturer's data to determine the load capacity in kg. This value can often be found on the side of the tyre adjacent to the ply rating indication. It is becoming more common for ATV and turf tyres to be marked up in this manner. They are usually dual marked with their traditional inch dimensions, but if you are handy with a calculator, it's possible to convert from one to the other. For example, a 255/60-10 ATV tyre would be 255mm wide, have a 153mm sidewall height and fit a 10" rim. Converting these dimensions to inches would give us 10" width, 6" sidewall height and 22" (10" rim plus two lots of 6" high sidewalls) overall height. In traditional ATV tyre size marking, this would become a 22x10.00-10.

This is the most simple size marking. The first part, 3.00, is simply both the width of the tyre and the height of the sidewall of the tyre in inches. The second part, -4, is the rim diameter in inches. So a 3.00-4 tyre would fit a 4" diameter rim, be 3" wide and 3" tall on the sidewall. Therefore, the overall height of the tyre would be 10" (4" plus 3" plus 3"). If your wheels are even deeper than the longest valve you can find, you can buy valve extenders to add length to your valve. There’s a range of lengths available: Zipp for example makes extenders from 27mm up to 98mm long. So, a 145R10 is a radial tyre, 145mm wide, sidewall height of 116mm (80% of 145mm) and fits a 10" rim. A 195/50R13 tyre would be 195mm wide, have a sidewall height of 98mm, and fit a 13" rim. The approximate overall height of the tyre can be worked out by converting both dimensions to either mm or inches, and adding the rim diameter to twice the sidewall height.On bikes, Schrader valves tend to be used on lower pressure tyres, such as kids's bikes and mountain bikes. These are the same valves used on all motor vehicle tyres and are often referred to as ‘car type’ valves. Schrader valves have a core that is sprung loaded, and the central pin can be depressed with a narrow object to release air from the tube. The spring mechanism keeps the valve closed. If you are looking to change your tyre size, the height and width may be selected according to your needs, bu the last figure, the rim diameter, must be the same, unless you are buying new wheels too! This is the traditional method for marking car and van tyres, so is also used quite often for trailer and caravan tyres. The first part is the width of the tyre in mm, the second part, if present, is the height of the sidewall expressed as a percentage of the width, and the third part is the rim diameter in inches. If there is no percentage indication in the tyre size, the tyre sidewall height is taken to be 80% of the width. You may sometimes see a tyre with the 80% in the size eg. 155/80-13. The 'R'. when present within the size, means the tyre is of radial construction. 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?