- It's 2021 and we have come a long way since
Carl Benz-amin patented the first car in 1885.
Teslas can hit 60 miles per hour just two seconds.
- Why? - Freaking One drivers
experience more G forces than astronauts,
and we got road cars,
plural,
that can do 300 miles per hour.
- Why? - But none of those
amazing things would be possible without the one part
that actually touches the road.
That's tires.
And those, they've come a long way too.
Like my grandma, when we kicked her out of the car
and made her walk home.
So today, we're going to figure out the secrets
behind tires' grip.
Why there's so much variation in tread
in what seems like a pretty simple design
and why some tires cost more than your average new car.
As Canaan wants me to say, let's figure it out.
Burn out face. (man squealing)
(laid-back music)
Thanks to Keeps for sponsoring today's video.
- [Nolan] Trick or treat.
- Jerry get the door.
I'm doing it, ma.
- Trick-or-treat.
- Oh, Nolan!
What are you supposed to be?
Whatever it is, it's terrifying.
- I'm you, Uncle Jerry. See?
Eh, I'm Uncle Jerry.
I'm going bald.
You're crazy, Dave, you freaking bird.
(bird chortling)
- Are you crazy, Dave?
Okay, number one, I would never say that.
I would say I'm one of the two out of three guys
experience some foreign male pattern baldness
by the time I was 35.
And number two, you're not even bald.
You look like you actually use Keeps.
See, Keeps makes hair loss prevention easy
by giving you access to real doctors online.
Plus, they'll ship you your medication to your door
every three months.
So don't trick your follicles,
treat them by going to Keeps.com/B2B
or click the link in the description to receive 50% off
your first order.
- Should have used Keeps.
- See, Uncle Jerry, you're the best selling costume
this year. - Hold on, Nolan.
Are you saying somebody is making money from this?
Dave, get my lawyer.
A tire's job is to make grip.
And that idea isn't frigging new.
Thousands of years ago, leather, even iron were added
to the surface of wooden wheels to aid in traction.
But the basic design for inflatable rubber tire
is only about 170 years old.
From the outside, it might look like a tire is just
a single piece of molded rubber.
And some of the first ones actually were.
But modern tires contain just 20% natural rubber
and can include up to 200 other chemicals in the compound.
It might also seem like the key to grip is all
in the tread too since that's the part that actually
touches the road.
But they're actually (man burps)
excuse me, three factors which explain how a modern tire
does its job.
The construction, which supports the tread,
the compound it's made from and its tread pattern.
So to see how tires produce grip,
we need to look at all three.
So over decades of the structure of the tire
has changed a bunch.
Tires have as many as 25 individual components
that have to be manufactured separately
and bonded together during the construction process.
Every modern tire share some basic parts though.
There's the obvious stuff you can see like the tread,
which is designed to make contact with the road,
and a sidewall, which has dozens of letters, numbers,
and symbols, each of which tells you something
about that tire.
But the parts you see are all supported by parts you can't,
unless you have x-ray vision like me.
So to understand grip, we've got to look
from the inside-out.
With tires, just like people and calzones,
what's inside counts.
And the parts of a tire that you can't see
are doing a lot of work.
The structure and basic shape is provided by what's called
the carcass.
The carcass is made of rubber coated fabric,
usually polyester.
Fine strands of textile are woven together
to give the tire a strong but flexible base.
These are sometimes called cords,
and a tire that is corded is one that has been worn
or damaged to the point that the fibers are visible
from the outside.
Because the carcass determines how much weight
and inflation pressure attire can withstand,
visible cords mean the internal structure
is no longer capable of doing that job safely.
And driving on corded tires is incredibly dangerous.
Here's a picture of a motorcycle
that I busted through the cords.
You can look at it.
See it as a little metal strands?
That's it.
If you want some fibers to keep your own carcass
from showing, you should check out this new shirt
from Donut.
- I'm super excited to introduce the brand new,
mo powa,
redesigned,
T-shirt.
So new in fact,
that I don't even have one yet.
But thanks to movie magic,
I do?
- Whoa, is that the new Donut Mo Powa shirt?
- Yes.
(man chuckling)
Go to DonutMedia.com, get yourself one.
I'm super excited about this.
Sign up for our mailing list.
We're dropping a new item every week.
I love you.
- Did you see that? See how we did that?
That's called product integration.
In addition to fabric, tires also contain metal.
At the base of the sidewall is the bead,
which contains a wire.
The air pressure inside the tire presses the bead
into a groove on the wheel in that rigid metal wire
makes sure the tire doesn't pop out of that groove.
There's also the belt.
The layer between the carcass and the tread.
That's usually made from a combination of nylon
and strips of steel often in a criss-cross
or lattice pattern to give it strength.
Expensive tires may even include Kevlar
for even more strength and puncture of resistance.
The fibers in the carcass are laid perpendicular
or radially to the direction of the tires' travel
and they act like Springs to absorb bumps from the road
and provide a comfortable ride.
But radial fiber wheels don't provide much support
to the tread.
The steel belt works together with the carcass
to make sure that the tire is rigid enough
to stay in contact with the road when going over bumps.
In other words, it maintains grip.
Nearly every tire since the 1960s uses this combination
of radial fibers and steel belt.
But back then, it was a revolutionary design.
It's why modern tires are sometimes called
steel belted radials to distinguish them from older designs
that lack those features.
Okay, now that we know the basic components inside of a tire
and how these support the tread to maintain grip,
let's look at the chemicals inside the tread itself
and why those are so important.
I just taught you guys a little bit of sign language too.
School's in session, mother.
The majority of attire is composed of 20% natural rubber,
combined with synthetic rubber and other chemicals
to make a material that grips.
The exact mixture of those chemicals is a tires compound
and creating that requires a special process.
Vulcanization.
Mesa loved the new Star Wars movie.
The inflatable tire was made possible by the discovery
of this process by Charles Goodyear
in the 1830s.
The tire company, Goodyear showed up about 40 years
after he died and the founders were completely unrelated.
They simply just use his name.
They're just like, hey.
Kind of like Tesla. (man laughs)
Exactly like Tesla.
What am I talking about?
Kind of? It's exactly like Tesla.
Incidentally, Goodyear made this discovery
while he was in prison.
See kids, you can learn in prison too.
(upbeat music)
Let's play a little game.
See if you can guess what he was in for.
Is it,
one, impersonating a Duke,
two, owing some guy money in south Philly,
or three, public endangerment for riding an ox
while intoxicated?
We're going to let you know at the end of the episode.
Vulcanization is important because for tires,
natural rubber is problematic like Nolan.
Boy's always getting into something.
It's only pliant within a narrow range of temperatures.
When it's too cold, it gets very hard and can crack.
But when it's too warm, it gets soft
and can be easily punctured.
Vulcanization is the process of heating rubber
with other chemicals so that they bond together.
These chemicals include synthetic rubbers,
which we talked about,
and they're pliant at different temperatures
compared to natural rubber.
You got carbon, which increases resistance to wear,
and it transmits heat for more even tire temperatures
and gives tires their black color,
helping them resist UV damage.
Then you got silica, which decreases rolling resistance
to reduce noise and improve fuel economy.
The final mixture of the compound has texture
and thermal properties different from natural rubber.
And these will determine how well the tire grips.
As you expect, the more complicated a compound is to produce
the more expensive it is.
But the complicated compounds that you find in, say,
a Formula One tire can produce huge amounts of grip.
But what is grip really?
Now we talk about grip all the time on the channel,
but do you know what it really is?
If some were to come up to you and say,
"Hey, I'll give you $100
if you can define what grip is."
Do you know?
Probably not.
But I'm going to tell you.
So if anyone ever comes up to you with a $100 bill,
you can look like a smarty pants and get $100.
So grip is just friction or resistance to sliding.
And the amount of grip between two surfaces
can be expressed as a number, the coefficient of friction.
If that number is close to zero,
it means there's very little grip or friction
between the objects.
And it takes very little force to slide one
across the other.
Steel and ice, they have a coefficient of friction
of just 0.03, which helps explain how the metal blades
on skates can glide over ice.
If the coefficient of friction is closer to one,
that means there's a lot more friction between the objects.
One also happens to be the coefficient of friction
between rubber and concrete.
It's also worth mentioning that all of these values
can change if one of the objects has water on it.
The wet coefficient of friction in between
rubber and concrete is just 0.3,
meaning it requires 70% less force
to make rubber slide on it.
That's going to be important in a moment.
So just stick with us.
But water isn't the only thing that changes
the coefficient of friction.
And in fact, the numbers I've mentioned so far for steel,
ice, rubber and concrete, they're just approximations.
That's because friction also depends on the roughness
of a surface.
And the roughness of asphalt is why texture
and temperature matters so much for tires' grip.
If you've ever fallen off a bike or a skateboard,
then you know that asphalt isn't smooth, it's rough.
It's surface is rough.
It contains lots of small peaks and valleys.
If you are driving around with completely hard,
perfectly smooth tires, like one made from iron,
it would be nearly impossible to turn
because you'd have no grip.
In part, that's because of the relatively low
coefficient of friction between iron and asphalt.
But it's also because the iron tire would have a very small
contact patch.
That's the amount of its surface which is actually
touching the road.
Because it's only in contact with the peaks of the asphalt.
That's a tiny amount of the total surface.
Vulcanized rubber flexes and deforms
under the weight of a car.
That pushes the rubber into all the valleys in the road,
increasing the total contact patch
between the rubber and asphalt to maximize grip.
The roughness of a surface also means
that at a microscopic level,
contact isn't perfectly parallel.
If you're turning, that means some portion
of the tire surface isn't resisting a lateral slide
across the road surface, it's actually pushing against
the road surface at an angle,
which creates even more traction.
The roughness of asphalt means, to work properly,
tires have to have compound's designed
to be soft within just the right range of temperatures
so it can sink into the road.
You can even feel the difference between tires
designed for different conditions.
A snow tire will feel slightly squishy at zero degrees C.
An all season tire, not so much.
But it still should have some give.
But a high performance summer tire will be rock hard
like my abs during hot boy summer.
I can make each individual one move.
And that brings us to one of the most important factors
of what makes a tire stick to the road.
That tread pattern.
You can easily see that a snow tire, an all season tire,
and a performance tire have different tread patterns.
Those differences are crucial to producing grip,
particularly when conditions aren't ideal.
Ideal conditions are what you find on a racetrack.
You got dry pavement, warm temperatures and clean asphalt.
Race tires, like you see in Formula One,
don't have a pattern in their tread
because they don't need it.
They only need to deal with one, consistent track surface.
But if you plan to take your car on a road or even off-road,
your tread pattern helps maintain grip
as conditions change.
A tire's tread pattern can be broken down
into a few parts.
The large, raised pieces of rubber that make contact
with the road, those are called tread blocks.
Or in the case of off-road tires, lugs.
Collectively, these are called ribs.
And because they have some ability to move around,
they allow the tire to flex and adapt to the road's surface.
Between the blocks and the ribs are grooves or voids.
The even smaller lines in the tread blocks are called sipes.
In most tread patterns, inside the grooves,
you'll also find wear bars.
These are there to tell you when it's time for new tires.
That's because when the tread wears down to those bars,
the pattern is only about 2/32 of an inch deep.
The blocks are shorter and less flexible
and the grooves are shallow.
The tread pattern's ability to produce grip
depends on those grooves because on the road,
that's how the tread pattern prevents hydroplaning.
Remember, we talked about water a few minutes ago.
Water can drastically change the coefficient of friction
between two objects.
In the case of rubber and concrete,
it takes less than a third of the force
to make rubber lose grip on wet concrete than dry concrete.
Water creates a barrier between those two objects,
preventing them from making full contact.
It fills in the roughness, which would add to grip,
and hydroplaning is what happens
when there's so little contact between the tire
and a wet road that it slides.
The lateral grooves and sipes on a tire give the blocks
a leading edge on its approach to the wet road surface.
And that edge acts like a rubber squeegee.
And the rest of the tread block then has an easier time
squishing even more water out from under itself
as it rolls onto the road.
But the tread blocks on a tire rotating at speed
are traveling too quickly to move enough water
to prevent hydroplaning,
unless the water has somewhere to go.
And that's what the longitudinal grooves are for.
These provide channels for water to get pushed out.
Out of the way of the tread blocks so they can make contact
with the road.
The same principle helps move small particles
of loose sand, gravel, or even snow away from the
tread block so the tire can grip the road surface beneath.
But what if there is no road surface beneath?
Well, if you're traveling off-road or in deep snow,
you need tires designed for that.
And these will have wide channels between the lugs.
All that extra space, it increases the contact patch
on loose surfaces.
Sand, gravel, or snow, it gets packed into those channels
by the lugs, making a contact patch that includes
not only the tread blocks, but the grooves as well.
Unfortunately, those same wide grooves,
they negatively impact grip on road because that empty space
takes away from the contact patch on dry asphalt.
So if you got a maul crawler, just put regular old tires
on it, otherwise you're just endangering all of us
with your tires and your decisions.
Tread patterns are always a compromise.
Like me and Catherine on Friday nights
when it comes to where we want to eat dinner.
She always wants to go to some fancy, hipster place
and I just want to go to the Rainforest Cafe.
They have animatronic monkeys and tigers,
and they shoot mist at you,
flashing lights that simulate a thunderstorm.
And you could be eating your jungle nuggets
and a dude could have a seizure.
It could happen.
That's why I go there.
A tread pattern with a large contact patch for dry asphalt
will only have grooves capable of moving small amounts
of water and can be overwhelmed in a downpour.
A tire which can move large amounts of water
has to have large grooves, and therefore
a reduced dry contact patch.
But tires have had 170 years to evolve.
And there are ways to reduce these compromises
with cleverly engineered patterns.
Most tread patterns on passenger tires are fully symmetric.
That means that the tread is the same on the left
and the right side, coming and going.
It doesn't matter which way the tire is rolling
or how it's mounted on the wheel,
the amount of grip remains the same.
But symmetric tires don't produce the most grip,
and that's why more expensive tires designed especially
to maximize grip will have a directional tread pattern.
That's designed to roll in only one direction
and lateral grooves in the tread will often be replaced
by ones that make a V-shaped.
A rolling tire doesn't make contact with the road
like a squeegee on your windshield.
The center of the tire actually touches down first
and then stays in contact with the road longer.
The V-shaped grooves take that into account
and they can channel more water more efficiently
away from the tread blocks.
The downside of directional tires,
apart from being more expensive,
they can't be rotated diagonally on a car
without being removed from the wheels
and flipped 180 degrees.
Which is why I hate them!
There's still one more trick to making grip
with tread pattern and that's asymmetric tires.
Those have different patterns on the inside
and outside portions of the tread.
That's because the contact patch isn't always
on the same part of the tread.
When cornering, contact shifts to the outside edge,
so tires can be made with wider blocks on the outside
to maximize grip.
They can even be made using different compounds
on the inside and outside parts of the tire.
In fact, modern tires can include up to
12 different compounds.
Asymmetric tires are often directional as well,
meaning greater water evacuation.
Now you probably guessed that means that they're expensive
and you'd be right.
But if you want optimal grip
for a specific set of conditions,
an asymmetric directional tread pattern
is the pinnacle of tire evolution.
(electronic music)
And if that set of conditions means you going
250 miles per hour in a Bugatti Veyron,
be prepared to shell out $42,000 for a set of tires.
More than the average cost of an entire car.
We did a whole episode on B2B of those very special tires.
Click here to check it out.
But there's still one very important question
that needs an answer in this episode.
Why does every tire have tread that looks different?
Even two tires in the same performance category
with very similar amounts of grip in similar conditions,
they can look drastically different.
Why is that, Jer-bear?
Well, tire tread is also designed to look good.
(man shouts)
Some of the reasons that the tread on your tires
look the way it does is simply
marketing.
But that doesn't mean that the grip is compromised.
Just like an actual evolution, the evolution of tires
is incredibly complicated, it involves so many factors
that it turns out there are lots of equally good ways
to solve the same problem.
So two tread patterns, or even two compounds
that have significant differences can produce
about the same amount of grip.
A big reason why some tire tread looks
like a Cubist painting or another tread looks
like a tribal tattoo,
it's just aesthetics.
Oh, and Charles Goodyear,
yeah, he went to prison because he owed some guy money.
Got your answer. Was that what you guessed?
If it wasn't, I'm sorry.
You lose!
Okay, so I got a question for all of my engineers,
scientists, smarty pants out there.
If you look at the frictional force equation,
it's frictional force is equal to μFn,
which is the normal force.
Now I know that, as a race car driver,
if I have bigger tires, I have better traction,
but the frictional force equation has no surface area
component in it.
So why is that?
Why do people like drag racers run wider, fatter tires
for more traction?
If you can answer that question, the first person to do it,
put a comment down below.
I'll send you a T-shirt.
It's got to be right though,
If it's wrong, no T-shirt.
If it's right, I'll send you a T-shirt.
Good luck my engineering foe.
So much goes into tires,
we couldn't possibly cover it in just one episode.
They're incredibly complex.
And it's taking billions of dollars in research
and development to evolve the humble rubber tire
into what it is today.
Thank you guys so much for watching this episode of B2B.
Answer my questions down below.
I want to see who is a smarty pants in this group.
Come follow us over on Instagram and TikTok
at Donut Media.
Follow me on Instagram at @jeremiahburton
and follow me on TikTok @silenceofthelambda.
Thank you guys so much for watching this episode.
Till next week.
Bye for now.