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Tire Size

Apr. 9 2021 News By Lloyd Belt Automotive

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Learn what the different letters and numbers molded on the side of your tire’s wall means which includes tire type, width, aspect ratio, construction, and diameter.

Tire Type

The “P” listed first on the molding indicates that specific tire is intended for passenger vehicles with United States standards. When there are no letters at the beginning of the Tire Size, that means it’s a Euro-metric tire which may have different load capacities than the standard for vehicles in the United States. “LT” can be at the beginning or the end of the Tire Size which is dedicated for light trucks only; the air pressure for these tires are notoriously higher than passenger tires.

If you are unsure what type of tires you need for your vehicle, you can check your owner’s manual, or someone from our team can help you find replacements that will fit your vehicle’s necessary tire size.

Tire Width

Tires are measured by width in millimeters which are the next numbers in the Tire Size. As an example, if you see P235/75R15 they would have a width of 235 millimeters.

Aspect Ratio

The height of tires is measured in relation to the tire’s width which is the numbers right before the aspect ratio. As an example, if you see P235/75R15 the height of the tire is 75% of the tire’s width. If your vehicle requires a larger sidewall, you will need to choose a tire with a larger aspect ratio.

Construction

When the next letter on your Tire Size is an “R,” that means the layers within the tire run radially.

Wheel Diameter

The wheel diameter tells you the size of the wheel that the tire size is intended to fit. For example, a Tire Size reading P235/75R15 will only work on a wheel if it has a 15” diameter.

Some other ratings you can find on the Tire Size molding include:

  • Load Index – The load index is the largest amount of weight that a specific tire can sustain when it has the proper air pressure. If you need to find the load index, you’ll be able to see it on the sidewall being featured in both kilograms and pounds.
  • Speed Rating – The speed rating is how high of speeds this style of tires can sustain. We always encourage our buyers to drive the speed limit for legal and safety reasons, but knowing the top speed capacity is a useful description depending on what type of driving you regularly do whether it’s primarily on the interstate or in town.
  • DOT Symbol – We suggest if you’re going to buy tires, make sure it has “DOT” on the sidewall of them which means they are approved in all categories by the Federal Motor Vehicle Safety Standards in the US.
  • Tire Identification Number – Following the DOT symbol, you’ll find the tire identification number which is a series of 12 numbers and letters that show the location of the factory it was manufactured in, as well as the week and year. Uniform Tire Quality Grading (UTQG).
    The Uniform Tire Quality Grading is a rating system that can educate you on tires and their specific treadwear, temperature grade, and their traction level.