- 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.
