Bold School: The Basics of Tires, Part 2

Earlier this week, we brought you a few of the basics of tires. There are various components to a tire's grip and specific tires for specific conditions. That's all well and good but, once you've figured out the right style for you, how do choose the specific tire? The most important part of that selection process is being able to identify the tire based on the sidewall ID. It may seem like hieroglyphics or a Dewey Decimal system, but once you get your head around it, picking out the right tires won't be something to avoid! Look at the side of your tire, you'll see something that may look like this:  
Bold School: The Basics of Tires, Part 2
Gibberish, right? Wrong! Those numbers are a quick easy reference guide, here's how it works/ The numbers included in there are tire width, aspect ratio, speed rating, tire construction, and rim diameter. See:
Bold School: The Basics of Tires, Part 2
So what does that mean? Glad you asked. Those numbers pertain to various key elements of the tire, as seen in the diagram below:
Bold School: The Basics of Tires, Part 2
Section Width: Distance between the sidewalls of an inflated tire. That figure is without any load on the tire and excludes any protrusions (like those little rubber doodads). Section Height: Distance from rim seat (the inside edge of the rim) to the outer edge of the tire. Once again, unloaded.  Aspect Ratio: section height divided by section width, and multiplied by one hundred. Speed Rating: Short answer is that its the speed up to which the tire is safe to operate under a load. Radial: A type of tire…discussion for another day Rim Diameter: …if you have to ask…. So for our tire, 185/70SR14 now means the following:
Bold School: The Basics of Tires, Part 2
185mm= Section Width in Millimeters 70= Aspect Ratio (129.5 / 185 = 0.7 (x 100) = 70) S= 112 MPH Speed Rating R= Radial Construction 14in.= Rim Diameter in Inches Well class, we could delve much more into each element at play here, but for now that should get you started in your quest for tires. Next time, we'll look at performance tires and why you need them if you don't want to look like a chump on the track!

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