How To Read A Tire Sidewall With Toyo Tires

The sidewall of every tire carries so much information on such an important topic. Yet, many times, we relegate that information into the same urgency as the owner’s manual for our cars. You HAVE eventually read your owner’s manual, haven’t you?

The information on the sidewall of our tires is federally mandated, but that doesn’t mean that it’s only applicable to legislators and lawyers. That information tells us so much about our tires’ intended uses, that we would do well to go beyond simply the tire size column.

Toyo Tires has created an informative video that takes you through the process of decoding these not-so-cryptic inscriptions found near the near-and-dear wheel of choice on your favorite ride. Once you know what they mean, future decoding is much simpler, and can help you when choosing the next set of tires, as well as shopping the swap meets for a used set of skins. They have even more information on their website.

One of the main tidbits of information we like to talk about are a tire’s speed rating. Toyo adds this caveat to their Speed Rating Chart on their website: “*Any tire with a speed capability above 149 mph (240 km/h) can, at the tire manufacturer’s option, include a “Z” in the tire size designation (e.g., 245/40ZR18). If the load index and the speed symbol are not included, the tire manufacturer must be consulted for the maximum speed capability (245/40ZR18 speed capability is greater than 149 mph [240 km/h]). If a service description is included with the size description, the speed capability is limited by the speed symbol in the service description (i.e., 235/45ZR17 97W = maximum speed 168 mph [270 km/h]).

A further caveat reads: **Although no upper limit speed is specified, the indicated tires nonetheless have limited rated speed capability. Call (800)-442-8696 (PST) or (888) 444-8696 (EST) for a referral for more technical information.”

 

This speed rating chart is likely the second-most important information to enthusiasts. We’re performance enthusiasts, right?

As mentioned, and as you likely already know, tires are marked with their sizing. But another equally-important piece of information is knowing how many times the tire you’re looking at has already rotated around the sun. The industry standard pretty much settles on six years before a tire becomes questionable, but some attest you can get up to 10 years, so long as you inspect the tires regularly after the fifth year.

 

Other bits of information garnered from the hieroglyphs on the sidewall will inform you of the load capacity of the tire. With so much tire-swapping among enthusiasts, it goes without saying that more than a few tires have transferred to a vehicle that they weren’t intended to be used upon. At that point, the viability of the tire for the intended purpose does become the playground for  lawyers and legislators, and we’d all like to avoid that, if possible.

The load index number and speed symbol correspond to the maximum load-carrying capacity of the tire and its maximum speed capability.

Check out this quick video prepared by Toyo Tires and then go check your set of tires. You may be amazed what you find. If you unearth some really enlightening information, feel free to share in the comments section below. We’ll wait ‘til you get back from the garage.

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About the author

Andy Bolig

Andy has been intrigued by mechanical things all of his life and enjoys tinkering with cars of all makes and ages. Finding value in style points, he can appreciate cars of all power and performance levels. Andy is an avid railfan and gets his “high” by flying radio-controlled model airplanes when time permits. He keeps his feet firmly grounded by working on his two street rods and his supercharged C4 Corvette. Whether planes, trains, motorcycles, or automobiles, Andy has immersed himself in a world driven by internal combustion.
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