Vehicle Maintenance 101: Tires Part 1: Tire markings

Tires: Arguably one of the most important parts of your car. They not only determine how well the car rolls, but also how effective the brakes are, how well the car tracks in snow and rain, and even how well the suspension works. And when it comes to selecting a tire to buy, there are hundreds of sizes, thousands , if not millions of combinations of speed rating, weight rating, treadwear, traction levels, brand, tread pattern and even rubber compound. You've seen this first hand if you've ever walked into a tire store and seen the rows and rows of tires. So, to help reduce the confusion, here is our guide to buying tires.

The first thing you need to determine is the tire size. Most vehicles will have the factory tire size already installed. So, you can either look for the tire size on the sidewall of the tire, or find the Tire and Loading information label in the Drivers Front door frame. This car, a 2012 Hyundai Sonata, calls for a  P215/55R17 tire, inflated to 33psi.

The “P” indicates a tire meant for Passenger vehicles. Other options include “LT”, meant for Light Trucks (pickups and SUV’s), “T”, meant for temporary use as a spare, or “ST”, which are trailer tires. The next number, “215”, is the section width, in millimeters. The section width is just the widest point in the cross section of the tire. 215mm translates to about 8 ½ inches. The “/” indicates that the next number is a percentage of the section width. The “55” indicates that the sidewall of the tire (measured from the rim to the tread) is 55% of the section width, or 118.25mm (4.65 inches). The “R” indicates that the tire has a Radial-type internal construction. Other things you could see are “D” for Diagonal / Bias-ply tires. These are commonly found on cars from the 1950’s to the 1980’s. A “B” would indicate a rather old, and nearly impossible to find “Belted” tire. Sometimes, you might see a “RF”, which indicates a runflat (A tire that can support the weight of the car with zero air pressure.) or a “ZR”, indicating a “Z-Rated” Tire. I’ll get to that a bit later. The “17” indicates rim diameter (measured at the bead-seating surface, not the largest diameter.) On some truck and off-road applications

Next, we see these numbers: "93V" and "M+S". 93V is the load and speed index, and the M+S, standing for "Mud and Snow", indicates an All-Season tire. The graphics below, via, indicate what the Load and Speed ratings indicate.

The series of numbers here (in the US market, anyway) indicate both US Department of Transportation Certification and tire serial number. The "1616" indicates that the tire was manufactured in the 16th week of 2016.

This text indicates maximum load (650kg or 1433 lbs) and Maximum tested inflation pressure (300kPa or 44 psi). For inflation pressure, use the label in the drivers door opening.

This indicates the tire construction materials and reinforcements.

These graphics also indicate an All-season tire.

This symbol indicates a winter tire.

This Studdable snow tire has a tread pattern geared toward displacing snow.
Most tires will also have a treadwear, traction and temperature rating. (This is a different tire). The Treadwear rating number indicates mileage ratings. In general, the Treadwear rating number, the longer the tire will last. It's essentially a percentage of life relative to the manufacturers test tire. a rating of 480 indicates that the tire should last 4.8 times longer, or 480% longer than the test tire. The Traction rating refers to how well the tire grips on wet Asphalt, with ratings ranging from a C up to an AA. AA being the best. And the Temperature rating  indicates the tires ability to maintain traction at speed without overheating. So an A-rated tire should perform at speeds over 115mph without getting too hot.
Now that we have gone over all of the data, the next thing to decide is what Brand and tire model you want. This Kumho tire is the Factory tire on the 2012 Hyundai Sonata. If you want to know what tire was factory equipment on your car, just call a tire store or the parts department at the dealership that services your brand.

The next thing to consider when tire shopping is what you need the tire to do. Are you just looking for a good tire to last you 60,000 miles, or do you require the smoothest, quietest ride possible? Are you looking for a good Summer-only High-performance tire or a dedicated Slick tire? An All-Terrain mud tire or a Snow tire? Each tire is good for it's own thing.

A standard All-season touring tire is ideal for 80% of passenger cars on the road. Pretty much any car with wheels between 13" and 17" in diameter will use an All-season touring tire. Cars that are more performance-oriented will call for a High-performance or Ultra-Hogh-Performance All-season or Summer tire. Many trucks, due to their weight, require LT-grade tires, which have an extra reinforcement ply in it's construction to deal with the extra weight of the vehicle.

And, I feel I need to mention this, an All-Season Tire might perform well in all 4 seasons in more moderate climates, but in places that see temperatures below 45 degrees consistently, a winter tire is advised. The colder the weather, the less effective an All-Season tire's rubber compound becomes at gripping the road.

An Agressive mud tire might not perform that well in the snow, either, for the same reason.

For any additional information on tire sizes and data, check out Also, to check out tire pricing or to order tires, TireRack is one of the leaders in Online Tire shopping.

Coming Soon: Wheel Sizes.



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