Frequently asked questions
BFGoodrich answers your most asked questions.
FAQ
The inner liner, carcass ply, beads, belts, sidewall, and tread. The inner liner holds air. The carcass ply is textile fiber cords bonded into rubber and is largely responsible for the tire's strength. The beads clamp firmly against the rim. The belts stabilize the tread. The sidewall protects against impacts. The tread provides traction and cornering grip while resisting wear, abrasion, and heat.
The sidewall flexes with every rotation, thousands of times per mile. Any patch or plug bonded to a surface under that much repeated flexing eventually separates, and when it fails it fails suddenly. That is why a cut through the sidewall cords, a bulge, or a sidewall puncture means replacement regardless of how small the damage looks.
The carcass ply sits above the inner liner and is made of thin textile fiber cords bonded into rubber. These cords largely determine the tire's strength. Ply rating is a legacy term for load capacity. On modern tires, the load index and load range letter on the sidewall are the accurate way to compare strength.
Thick sidewalls add toughness so you can take on all but the most extreme trails. Sidewall damage is the leading cause of trail-ending flats because rocks strike the tire from the side where there is no tread protection. This is a defining difference between an all-terrain or mud-terrain tire and a standard highway tire.
The sidewall is the area between the tread shoulder and the rim bead, the vertical face you see when the tire is mounted. It carries all the printed information: brand, tire line, size code, load index, speed rating, DOT date code, and any 3PMSF or M+S markings.
Related pages
Related articles
-
Tire Speed Rating Chart
Speed ratings are not just about speed. They correlate directly with ride comfort, treadwear, and cornering ability. Typically the higher the speed rating, the better the grip and stopping power, but the shorter the tread life. Ratings run from A at the lowest to Y at the highest, and the chart is not strictly alphabetical: H sits between U and V, a holdover from when H stood for high performance.View more -
How to Read a Tire Sidewall
A tire’s sidewall is pretty much what it sounds like – the outer and inner “walls” on the sides of a tire, if facing a tire on its side. Every sidewall has its own unique information that is divided into four main sections:View more -
Find the Right Size Tire for My Car
Your correct tire size is printed in two places: the sidewall of the tires on your vehicle now, and the OEM placard inside your driver's side door. That same placard gives you the correct cold inflation pressure. For an accurate pressure reading, check when the tires have not been driven for three hours, because friction creates heat and heat raises pressure, giving you a false high reading.View more