I'm looking for a table of the old alpha-numeric tire codes used in the 1970s that gives the actual dimensions (section width, section height, and/or overall diameter) in inches/mm and load rating for each size. I AM NOT LOOKING FOR A CONVERSION CHART that cross-references old designations to the nearest modern size. PLEASE DON'T REPLY WITH A CONVERSION CHART.
From Wikipedia:
"Starting in 1972 tires were specified by load rating, using a letter code. In practice, a higher load rating tire was also a wider tire. In this system a tire had a letter, optionally followed by "R" for radial tires, followed by the aspect ratio, a dash and the diameter – C78-15 or CR78-15 for bias and radial, respectively. Each diameter of rim had a separate sequence of load ratings; thus, a C78-14 and a C78-15 are not the same width. An aspect ratio of 78% was typical for letter-sized tires, although 70% was also common and lower profiles down to 50% were occasionally seen."
The leading letter in this style of code is usually referred to as the "load rating" and is followed by the two-digit aspect ratio. The number after the dash is the rim diameter. This system explicitly gives the aspect ratio, but there is no width or height given in the code that the aspect ratio can be applied to. Although the first letter is referred to as the "load rating" it seems to imply that it also indicates the width of the tire. For example G78-15 and H78-15 do not convert to the same size modern P-code tire, so that first letter obviously holds more information than just the load capability.
I'm looking for a chart that translates the letters to physical measurements of the section height/width. Something a tire shop in 1975 probably had in their literature. Don't care about the nearest modern approximation. Just want raw dimensions. Thanks!
From Wikipedia:
"Starting in 1972 tires were specified by load rating, using a letter code. In practice, a higher load rating tire was also a wider tire. In this system a tire had a letter, optionally followed by "R" for radial tires, followed by the aspect ratio, a dash and the diameter – C78-15 or CR78-15 for bias and radial, respectively. Each diameter of rim had a separate sequence of load ratings; thus, a C78-14 and a C78-15 are not the same width. An aspect ratio of 78% was typical for letter-sized tires, although 70% was also common and lower profiles down to 50% were occasionally seen."
The leading letter in this style of code is usually referred to as the "load rating" and is followed by the two-digit aspect ratio. The number after the dash is the rim diameter. This system explicitly gives the aspect ratio, but there is no width or height given in the code that the aspect ratio can be applied to. Although the first letter is referred to as the "load rating" it seems to imply that it also indicates the width of the tire. For example G78-15 and H78-15 do not convert to the same size modern P-code tire, so that first letter obviously holds more information than just the load capability.
I'm looking for a chart that translates the letters to physical measurements of the section height/width. Something a tire shop in 1975 probably had in their literature. Don't care about the nearest modern approximation. Just want raw dimensions. Thanks!
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