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ISO 5775 is an international standard for labeling the size of bicycle tires and rims. The system used was originally developed by the European Tyre and Rim Technical Organisation (ETRTO). It is designed to make tire sizing consistent and clear.
ETRTO sizes apply to rims and tyres for vehicles of all types, including bicycles. The great advantage of ETRTO sizing is that it is unambiguous; previously, nominal dimensions were used which were interpreted in different ways by different countries and manufacturers - a problem for the end user.
Prior to 1964, tires were all made to a 90% aspect ratio. Tire size was specified as the tire width in inches and the diameter in inches – for example, 6.50-15. [24] From 1965 to the early 1970s, tires were made to an 80% aspect ratio. Tire size was again specified by width in inches and diameter in inches.
In 1824, these units were replaced with a single system based on the imperial gallon. [a] Originally defined as the volume of 10 pounds (4.54 kg) of distilled water (under certain conditions), [b] then redefined by the Weights and Measures Act 1985 to be exactly 4.546 09 L (277.4 cu in), the imperial gallon is close in size to the old ale gallon.
The unit of volume, the gallon, has different values in the United States and in the United Kingdom – the US fluid gallon being about 0.83 imperial gallons and the US dry gallon being about 0.97 imperial gallons. The US fluid gallon was based on the wine gallon used in England prior to 1826.
Tire factories start with bulk raw materials such as synthetic rubber (60% -70% of total rubber in the tire industry [2] [3]), carbon black, and chemicals and produce numerous specialized components that are assembled and cured. The tire is an assembly of numerous components that are built up on a drum and then cured in a press under heat and ...
A United States National Highway Traffic Safety Administration (NHTSA) study in 2009 found that if 2% of the replacement tires would reduce their rolling resistance by 5%, there would be 7.9 million gallons fuel and 76,000 metric tons of CO 2 saved annually. [citation needed] (SAE J1269 and SAE J2452) performed on new tires.
For example, a bicycle tire pumped up to 65 psig in a local atmospheric pressure at sea level (14.7 psi) will have a pressure of 79.7 psia (14.7 psi + 65 psi). [ 2 ] [ 3 ] When gauge pressure is referenced to something other than ambient atmospheric pressure, then the unit is pound per square inch differential ( psid ).