You can read your tire like a book, if you know what all the codes mean, and it tells you a lot about what kind of tires you've got, or what kind of tires you're about to spend a ton of money on.
So let's learn how to do it.
The first thing you might ask is, what brand is it?
It's the biggest thing you'll see on here.
Some brands are very prestigious, other brands you've never heard of.
You go, who?
There are far more tire brands than there are tire companies.
For example Kelley tires, they're made by Goodyear.
Firestone, it's part of Bridgestone.
Uniroyal they're made by a division of Michelin.
So ask your independent tire shop, who makes this brand of tire?
It may not actually be a brand of a factory, now in this case I've got Continental tires, says Continental here, says Continental there.
In fact, it says Continental in different typefaces.
Who the hell's managing brand identity over there?
That's a whole another video, but I know right away it's a Continental.
What I want to get into is what is the specifications set of this tire?
And there, we turn to the biggest numbers first.
By the big numbers, I mean these guys here, it's something slash something.
In this case, 235/55.
The 235 is the width of this tire in millimeters, and it's about 25 millimeters to an inch by the way, just a ballpark that, over the ratio of its height as a percentage of its width.
Its profile or its aspect ratio if you will.
Really key numbers to figure out how big a tire you're getting.
And is it a tall tire, or kind of a low aggressive tire?
The next number is an R. You'll always see in our R, R is radial, all tires are radial these days.
17 is the next number, that is the bead diameter.
That's the diameter of wheel, this tire is meant to sit on.
Its across the metal part here, not the overall width of the tire.
Here's 99 and H, 99 is a load rating, H is a speed rating.
In and of themselves, they don't tell you anything, it's not 99 pounds or 9900 pounds.
It's just a number for a look up table, and a letter for a look up table.
In this case, 99 means this tire is good for up to 1709 pounds of load on it, and the H means it's designed to run it up to 130 mph without disintegrating.
You may also see some other letters on the tire.
P is passenger car, LT is light truck, T is temporary, typically for a spare, and ST is for a special trailer or just a trailer.
Continuing around on this tire you're gonna find the pressure information.
This one is commonly misunderstood.
You look at this and it says max inflation pressure 51 PSI, you go to the gas station you try to put 51 PSI in here, which you can probably do with a stout compressor, but you shouldn't.
That is the maximum pressure this thing will hold and stay seated on the bead on the wheel here.
What you wanna do is look up the actual pressure on your car, there's a label somewhere on any modern cards, it's typically on the fuel door or in the door jam.
And it's always in the owners manual, and it's gonna be much lower than that.
This car, I think is 34 PSI, what it's supposed to have in it, not 51, know the difference.
Okay, if that pressure information is the most commonly misunderstood, the next stuff is the most commonly ignored and shouldn't be.
It follows the letters DOT, DOT means this tire matches all the basic standards and specs for the US Department of Transportation, it is an authentic legitimate tire.
Then you've got a series of numbers after that.
These are the manufacturing lot number if you will.
You wanna register your new tires with those lot number data, so that you can be notified in case of a safety recall.
They notify people buy a lot or batch of tires, because they wanna narrow it down to the ones that might be bad.
We learned a lot about this between Ford and Firestone, a number of years ago.
And then the last digits in this DOT string, you'll see four of them in most cases.
In my case it's 4518.
This is my manufacturing date, it's the last group of 4. 45 means the 45th week of 2018, that's how that works.
If you happen to have a tire where the date code is only three digits, that's an ancient tire, and they don't do three digits anymore, they haven't for a long time.
That tire is too old to be on the road.
Fine for a show car, collectible that sits on a trailer, but don't be driving a three code tire in 2020 or later.
Finally, we get to the data that I think is the hardest to read.
It's usually in the finest print on modern tires it seems, and that is the UTQG, sexy acronym, right?
Universal Tire Quality Grading Standards.
The first one says treadwear, good, that's what I wanna know.
How long will this tire last?
This is a relative number, it's an index, in a minor 800, it's a good tires, higher numbers are better, but it doesn't tell you how many miles it's gonna last.
That 800 doesn't mean 80,000 for example, that would be pretty good.
Traction, graded like bonds, higher numbers better than let's say B or C or D.
Same thing with temperature.
I've got A here that's better than a B or, a C in terms of its temperature handling ability, to maintain performance in extreme temperatures.
These are very loose comparative grades.
As you can see, they don't really get into much detail, but they tell you something.
One more thing you can read on your tire, but it's not written in text or numbers, is the tread bars.
Let me find mine.
Here we go, they're really hard to see.
But if you look in the grooves of your tire, at some points around its circumference, you're gonna find little bumps that stick up.
Those are the treadwear indicators, you wanna make sure that by the time your tread is even with these little bumps, these tread bars, it's time to get new tires.
That's telling you where the minimum amount of depth is.
It's kinda like those squeal indicators on breaks, that tell you when it's time to get new brake pads.
Well, you can't do that on a tire, you do a visual thing instead.
That's what those bumps are, at certain points in your tread groups.
Okay, one more thing I'll tell you about tires that you can kinda read, but only if they're new.
I can't do that on this tire, is you might see some colored dots.
You might see a yellow dot for example.
Yellow means the place where the tires lightest.
Tires are pretty uniform, but they have a heavier point and a lighter point around their circumference.
As a result, they mark that so the light spot on the tire when it's mounted to a wheel can be matched up to the heavy spot on the wheel, which is a different mark.
It gives you a more balanced overall assembly, and requires fewer weights to get the whole thing balanced.
The other one you might see is either a red or a blue dot on a new tire, and that marks the high spot of its circumference.
That also allows the tire shop to align that with the low spot on the wheel.
Again, wheels aren't perfect either.
These are very minor, optimizing, sometimes shops don't pay attention to them, but if you've got a good shop to get a really nice car, you wanna pay attention to those when new tires go on.