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Tire Information - Size, Load, Speed Ratings


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This is just a 'Quick Reference' to help

out everyone when they go to buy some

new Tires.



Tire Size Calculator - ... Link (Miata)


Tire Size Calculator II ... http://www.discounttiredirect.com/direct/brochure/info/tmpInfoTireMath.jsp


Tire Size - Information




Sidewall Aspect Ratio


Typically following the three digits identifying the tire's Section Width in millimeters is a two-digit number that identifies the tire's profile or aspect ratio.


P225/50R16 91S


The 50 indicates that this tire size's sidewall height (from rim to tread) is 50% of its section width. The measurement is the tire's section height, and also referred to as the tire's series, profile or aspect ratio. The higher the number, the taller the sidewall; the lower the number, the lower the sidewall. We know that this tire size's section width is 225mm and that its section height is 50% of 225mm. By converting the 225mm to inches (225 / 25.4 = 8.86") and multiplying it by 50% (.50) we confirm that this tire size results in a tire section height of 4.43". If this tire were a P225/70R16 size, our calculation would confirm that the size would result in a section height of 6.20", approximately a 1.8-inch taller sidewall.



Uniform Tire Quality Grading (UTQG)


Treadwear Rating

Tempurature Rating

Traction Rating



Speed Ratings







Load Ratings





Tire Build Date





If I have forgotten anything, please remind me, and I will post it up ... :thumbs:

Edited by Stitches040 (see edit history)
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