3 ms·

take a look on how tires are measured, https://www.bridgestoneamericas.com/en/company/safety/choosing-tires/determining-tire-size https://www.bridgestoneamerica

• vel0city 4y ago
  I'd really love a reason for why they went with aspect ratio versus just sidewall height in inches. To me it just seems like more pain to try and understand the size of a tire, but I do imagine there was some good reason why it was measured that way.
  • tristor 4y ago
    The reasoning I've always understood is that the width of the tire is the primary thing that determines how it fits onto the wheel (assuming it's the correct diameter), and that different tires due to different tread block designs have subtly different heights, but in a way that is negligible, so aspect ratio allows you to have a standardized understanding of height without being so exact as to be confusing. E.g. a consumer knows that they need either a 245/40 or a 255/40 for their 9" wide wheel, and that in either case their speedometer would be correct (which is based on total height), but brand A and brand B at 245/40 have a .3" difference in height. It does make things difficult for folks that slam their cars though when they don't want to rub, because there's less margin for error so they really need to measure the height of the tire.