You did the hard part already. You found the size your vehicle actually calls for, you know the load and speed rating it needs, and now there are three tires in front of you that all fit. They are not the same price, they are not the same brand, and the person across the counter is waiting on an answer.
So what separates them?
There is a code molded into the sidewall of every one of those tires that answers a good part of that question, and hardly anyone asks us about it. It is a number followed by two letters, something like 640 A B. That is the Uniform Tire Quality Grading code, usually shortened to UTQG, and it is three separate grades stacked together: treadwear, traction, and temperature. Here is what each one measures, what it does not, and how to use all three when you compare tires.
Where to Find the Code
Look at the sidewall lettering for the word TREADWEAR, or a bare three-digit number followed by one or two letters. On a new tire the same information is usually on a label on the tread face. Federal regulation 49 CFR 575.104 is what puts it there, so it is required disclosure, not marketing copy.
The three parts, in the order they appear:
- Treadwear. A number, always a multiple of 20, describing relative wear rate.
- Traction. A letter: AA, A, B, or C, from highest to lowest.
- Temperature. A letter: A, B, or C, from highest to lowest.
Three grades, three completely different tests. Most of the confusion we hear at the counter comes from treating them as one overall quality score.
One thing to know up front: under the regulation, the tire manufacturer (or brand owner) runs the tests and assigns the grades, inside a procedure NHTSA sets and monitors. That makes the grades strongest as a comparison within one manufacturer’s own lineup, and softer across brands.
Treadwear: A Comparison, Not a Mileage Promise
The treadwear grade is the one people think they understand. Bigger number, longer life. That is close, but it misleads.
The grade comes from running a tire on a government test course of roughly 400 miles near San Angelo, Texas, and measuring its wear rate against reference tires. Two things follow.
It is a ratio, not a mileage figure. A 640 does not mean 64,000 miles. It means that tire wore at a certain rate relative to a reference tire on one stretch of Texas road. Your commute on the Eastern Bypass is not that course.
A small gap is not a gap. If one tire reads 500 and another reads 480 from different brands, that difference tells you almost nothing. A hundred-point spread within the same brand’s lineup is a real signal.
A high treadwear number also usually means a harder tread compound. Harder rubber wears more slowly, and it tends to give up some grip on wet pavement.
No treadwear grade saves a tire from a mechanical problem, either. A long-wearing tire can still wear out early from an alignment issue or a rotation that never happened.
Traction: One Narrow Test
The traction grade runs AA, A, B, C, and it measures exactly one thing: how well the tire stops in a straight line on wet pavement, tested on wet asphalt and wet concrete.
The test excludes cornering, hydroplaning resistance, acceleration, and dry grip. The regulation’s own required label text says the grade is based on straight-ahead braking and does not include cornering.
That matters during a summer afternoon thunderstorm, when you are taking a wet ramp or curve. You are asking the tire for cornering grip and resistance to standing water, which the traction letter never tested. An AA tire is genuinely better at stopping straight on a wet road than a B tire. Treat the letter as a wet-braking score, not an all-around wet-weather score.
Temperature: Heat Margin, and Why It Matters Here
The temperature grade is the one most often described wrong. It is not a rating of how much outside heat a tire can take.
It measures heat the tire generates itself and how well it sheds it. The tire is loaded to 88 percent of its maximum rated load and run on an indoor test wheel at stepped-up speeds. A tire that cannot finish the 500 rpm stage is graded C, one that finishes 500 is a B, and one that finishes 575 is an A.
Why does that matter in Montgomery? Because heat load on a tire adds up. Air temperature, pavement temperature, speed, load, and inflation pressure all feed the same total, and the temperature grade reflects how much margin the tire’s construction has before its materials start to suffer. July highs here average around 91 degrees, and dark asphalt in the summer sun runs hotter than the air above it. Add highway speed and a loaded vehicle, and the everyday summer drive uses more of that margin than it would somewhere milder.
The easiest way to throw margin away is low pressure. The U.S. Tire Manufacturers Association notes that underinflated tires generate excessive heat buildup and stress, which leads to irregular wear and internal damage. Our post on what Alabama heat does to your tires covers the pressure checks that go with this. The grade sets your margin; your pressure decides how much of it you keep.
Two Tires Side by Side
Put two tires next to each other. Same size, both correct for the vehicle.
- Tire A: 640 A B
- Tire B: 440 AA A
Shopping on the first number alone, Tire A wins easily. Read all three marks and the picture flips. Tire A claims a much longer relative wear rate, but its wet braking and heat margin are each graded one step lower. Tire B gives up tread life to take the top wet-braking grade and the top temperature grade.
That trade is not an accident. The harder rubber that earns a big treadwear number is often the same rubber that grips a little less when wet. Which one is right depends on how you drive:
- Mostly steady highway miles, moderate loads. Tire A’s wear advantage adds up over the years.
- Short trips, stop-and-go driving, summer showers. Tire B’s grades are doing work every week, while the wear advantage matters less because the miles add up slowly.
- A loaded work truck on hot pavement all summer. Heat margin and wet braking are the grades to protect.
Questions to Ask at the Counter
Size, load rating, and speed rating come first, always. Once those are settled, the code turns into a short list of questions:
- What did this tire trade to get its treadwear number? A high number with lower letters tells you where the engineering went.
- Are we comparing within one brand or across brands? Within a lineup, treadwear numbers are a fair ranking. Across brands, a small gap means very little.
- What is the temperature grade, given how I drive? Highway miles in August and heavy loads are where that letter earns its keep.
- What are the warranty terms? The grade is a test result. The written mileage warranty is a separate commitment.
Read the Codes With Us
Stop by 2718 Zelda Road, tell us what you drive, where you drive it, and how many miles a year you put on it, and we will read the codes on your real options together. You can also look up the sizes that fit your vehicle before you come in, or request a quote for current pricing.
