Metric tire size diagram showing aspect ratio section width and…

Tire Size, metric
To find the APPROXIMATE height of a metric tire, multiply the section width by the aspect ratio/100, double it, convert to inches, and add the rim size. For the ACTUAL size, look up the specs for the particular brand, model, & size on TireRack.com or the manufacturer's website.

Flotation tires are sized by nominal height in inches x nominal width in inches, construction type, and rim diameter in inches, like:
31x10.50R15 (about 31" tall; ~10.5" wide; radial construction; 15" rim)
35x12.50B17 (~35" tall; ~12.5" wide; bias-ply; 17" rim)

For more info, including the DOT code (date of mfr.), see these:
https://wfirm.com/complete-list-of-tire-dot-plant-codes
https://www.nhtsa.gov/equipment/tires#aging
https://www.nhtsa.gov/vehicle-safety/tires#the-topic-aging
The "DOT" number has three 4-digit groups; the first two contain the manufacturer ID & other proprietary info; the last group is the date code in this format: the production week (00-52) & 2-digit year. So the last group for a tire built the 40th week of 2012 would be "4012".

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Owner caption July 2003 · Photo 514 of 5000