Tires are among the most complex and critical components. They directly
affect cornering, braking, and acceleration, so safety and performance
depend heavily on tire design. Engineering tires involves balancing
grip, durability, and efficiency under varying conditions—a challenge
that requires advanced technology and careful testing. We'll dive into
the tire design process, including how engineers use computer modelling,
the different construction types and tread patterns, and the main
factors that impact tire grip and wear.
Initial Design Process (computer design)
Before making physical prototypes, engineers start with computer
simulations, which consist of 3D modelling the tire and calculating
forces acting on the tire (e.g., friction). They use computer
simulations to design tires and identify any early issues. Some of those
issues are: uneven tire wear, too much rolling resistance, poor grip,
and construction type. Calculating the forces acting on the tire helps
to get the tire one step closer to a working prototype in a time and
cost-effective way.
Construction Type
Two main construction types are used in tires: radials and bias plies.
Radials are ideal for day-to-day driving because they give better driver
feedback, less noise from the tires and longer tread life compared to
bias ply. Radials use steel belts perpendicular to the tire's tread,
while bias ply uses layers (plies) of cords at a 40-45 degree angle from
the tread. Bias-ply tires are better for strictly trail use because the
cords' design gives them a strong sidewall.
Tread patterns
Tread patterns are important because they can improve water ejection
away from the tread for more grip between the tire and the road. They
can also be specifically designed for certain surfaces (wet asphalt, dry
asphalt, and snow). There are multiple different tire patterns for
certain use cases. For simplicity, the tire patterns mentioned are the
combination of various tire tread types. Unidirectional Has a V-shaped
design to provide high grip on wet roads, mud and other slippery
conditions. The pattern allows water or slush to be thrown sideways away
from the tread, allowing the tire to have better grip in slippery
conditions and avoid hydroplaning. Asymmetrical Have various types of
grooves. Have high holding capabilities and improve traction on slippery
terrain. Lamborghinis and other performance cars use this type of tread.
These tires must be installed with specific care because they have a
different pattern on the inner and outer areas, which can affect
handling. Symmetrical Have the same pattern across the entire tire. The
shape on the inside and outside allows for high levels of efficiency,
speed and road safety.
Grip and Wear
In simple terms, tire wear is when the rubber on the tire wears down
when driving due to the friction of the road. Grip is self-explanatory;
it’s basically how well your tires can hold on to the road. Grip and
wear are inversely related. Multiple factors go into designing a tire to
balance both, but the most important one isn’t actually designing the
tire.
Factors That Affect Tires (most important to least)
Driving style is most important because the driver can do burnouts,
drift, take turns at 160 km/h+, and the tires will wear out much faster
since greater forces and more friction are acting on the tire. Road
conditions: If a road is more curvy, the forces acting on the tire are
higher, leading to accelerated wear. A smoother road means less friction
is acting on the tire, leading to less tire wear. Type of Vehicle: A
lighter AWD vehicle is best for minimizing tire wear since the torque
from the engine is evenly distributed to all four wheels. So the forces
acting on all four tires are lower, leading to even wear across all
tires. A lighter car, such as a Honda Civic or Toyota Corolla, means
less gravitational force is acting on the tire, so the tire isn’t
getting compressed from the force. Heavier cars are designed with
stronger materials, such as thicker, stronger steel belts to support the
weight and bigger tires so that there’s more tire to wear through.
Heavier cars have a higher wear rate when it comes to tires, but a
heavier car can wear out its tires in around the same time frame as a
lighter car. That's because the heavier car has bigger tires, so there's
more rubber to go through. If you took the rubber that was worn off from
the tires of both cars, you can see the heavier car’s tires wore through
their tires quicker. It's like someone with a sweet tooth (bigger
car/tire) and someone without a sweet tooth (smaller car/tire). The
person with a sweet tooth has 100 cookies (more rubber) at the start of
the month. The person without a sweet tooth has 10 cookies (less rubber)
at the start of the month. In this scenario, they’ll both have one
cookie left by the end of the month. The person with the sweet tooth
used more cookies (rubber) than the person without the sweet tooth.
Glass transition temperature: the temperature at which a compound goes
from a soft, rubbery state to a more rigid (glass-like) state.
Typically, a tire compound with a lower glass transition temp = more
flexible at low temperatures = less tire wear under normal driving
conditions. It allows the tire to stretch and deform with the road and
distribute all forces equally to ensure uniform wear across the whole
tire. If a tire doesn’t wear equally, you’ll have to replace it early,
even if it's a small strip. For example a small strip (5% of the tread)
on a tire is heavily more worn than the rest of the tire, leading you to
have to replace it because it wont throw water away as efficiently, it
won't stretch and deform properly/as effectively, leading to a loss of
grip which can be dangerous. Typically, summer performance tires have a
higher glass transition temperature than regular summer tires for
economy cars. At higher temperatures, the rubber will have maximum
contact with the road, bringing maximum grip.
Conclusion
When engineering a tire, everything is basically a trade-off. If you
want a higher grip, then you sacrifice wear and vice versa. If you make
a summer performance tire, it's not going to be good off-road or in
snow. If you make a dedicated snow tire, it won’t have as much grip as a
summer tire. That’s why we have multiple different tires for different
uses.
