EV Tires, Standing at the Inflection Point | Hankook Tire Global official site go to main
  • High-Tech
  • Mobility Culture

EV Tires, Standing at the Inflection Point

When humans first wore shoes, the reason they did so was to protect their feet. However, today’s shoes have been developed for various purposes and have a range of functions. The same can be said for tires. With mobility development, tires are further segmented into product categories to meet the specific requirements and needs. Let’s look at the current status of tire development for electric vehicles and where the practical experiences are being accumulated.

  • In the upcoming electric vehicle era, autonomous driving and an intelligent traffic system are highly likely to be interconnected.

A new paradigm for the vehicle has recently emerged. That is the electric car. We are now facing the time to wave goodbye to the internal combustion engines and wait for the transition to a new powertrain.

Electrified vehicles will bring more significant changes beyond switching fuel from fossil fuels to electricity. Let's take refueling as an example. Unlike traditional vehicles with engines that take minutes to fill with gas, it does not matter how fast the charging time is. Spending 20 to 40 minutes at a charging station is quite common. Therefore, the charging time needs to be considered when making trip plans. This also means drivers need to develop a new attitude towards living with EVs.

We also need to change our attitudes in regard to energy use. With conventional vehicles equipped with engines, the efficiency was related to the cost of operating a vehicle, whereas, with EVs, it directly impacts the range. Therefore, electric car drivers need to be more sensitive considering the charging environment.

  • Hankook Tire & Technology-Technology in Motion-EV Tires, Standing at the inflection Point-2
  • The conversion of car power from an internal combustion engine to an electric motor involves many changes.

Many things will change due to vehicle electrification. What’s more, if we enter an autonomous vehicle era with the wave of electric cars, driving, as we know it, may become a thing of the past. It isn't an exaggeration to call this the innovation in the mobility paradigm.

Even if the fuel and definitions of driving change, one thing that won't change is that the vehicle should be in contact with the ground. In other words, this highlights the importance of tires in driving. As the paradigm and attitudes towards vehicle use have changed, tires inevitably should also change. So, how should tires for electric cars evolve?

Interview

“Electric vehicles have different characteristics from the existing internal combustion engine vehicles and require the optimized tires. The goal of Hankook Electric Mobility Technology is to achieve a high load capacity, ultra-grip, and ultra-low noise.”

Hyunkyu Lee (New Tech. Benchmarking Project Researcher)

Hankook Tire & Technology-Technology in Motion-EV Tires, Standing at the inflection Point-3

Hankook Tire’s Kinergy AS EV developed by HEM* Technology.

*HEM (Hankook Electric Mobility) : Hankook Tire’s innovative future technology for tires

Q. Are tires for electric cars really necessary?

Absolutely. You can use regular tires sold in the market for your electric car. However, the problem is if tires directly match to the characteristics of the electric vehicles.

Electric vehicles differ from regular vehicles in many ways.
First, the vehicle platform is different. The engine is removed, battery packs are installed at the bottom of the chassis, and the electric motor is mounted. These changes impact the dynamics of the vehicle. Secondly, the batteries make cars heavier but display sportier performance due to the characteristics of the motor. Despite the added weight, the higher initial torque may create a feeling of a tire slip for the drivers, which means a higher tread grip is required. Third, these two significant changes affect the handling characteristics.

  • Hankook Tire & Technology-Technology in Motion-EV Tires, Standing at the inflection Point-4
  • Comparison between the combustion engine vehicle and electric vehicle platforms.

Q. Are there any characteristics to consider other than the dynamics?

A survey showed that the many electric car drivers have become more sensitive to noise. It may sound strange that the most concerning aspect of quieter electric vehicles is noise, but it logically makes sense. A lot of noise hidden under the engine noise becomes more noticeable. Therefore, the need to develop tires with lower noise levels was necessary.

Q. Electric cars are extremely silent. That might be why electric car drivers become more sensitive to the noises from the tires or road.

So far, this noise issue is relatively new to most drivers. When you first drive an electric car, you may find it strange not to hear the motor sound, and then the road noise appears. In particular, all you can hear at high speed is the sound of wind without the engine. So, it's understandable that drivers are taken aback by this. Again, tires will play a more significant role in the electric vehicle era.

  • Hankook Tire & Technology-Technology in Motion-EV Tires, Standing at the inflection Point-5
  • Hankook Tire Kinergy AS ev. has adopted designs specialized for electric cars, including noise reduction groove, ultra-high stiffness rib blocks, and cross-arranged edge blocks.

Q. Is there a way that tires can reduce noise?

Fundamentally, the noise can be reduced by tire patterns, pitch arrangement, and grip optimization. In particular, the lateral groove design can achieve significant noise reduction. Also, there is a form of technology to offset the noise frequency by forming grooves inside the tire tread block. As customers already know, we can attach foam-like sponges inside the tires.
Car manufacturers sometimes try to reduce the noise by designing specific patterns on wheels, but this may have a varying degree of impact per the pattern of the tires. Regardless, as a tire is the only component of a vehicle that comes into contact with the road, the most critical factor in noise reduction is the technology of the tire itself.

  • Hankook Tire & Technology-Technology in Motion-EV Tires, Standing at the inflection Point-6
  • The role of tires is growing important in electric cars in terms of the dynamic responsiveness and noise reduction.

Q. What changes are required to tires as the driving and dynamic characteristics have changed?

Most of all, as an electric vehicle is 150 to 200kg heavier than an internal combustion engine vehicle, the suspension setup changes accordingly. If the setup used for the internal combustion engine vehicles is replicated, the electric car sways more. This leads to a stiffer design, making some drivers feel uncomfortable. We are researching the best tire for electric vehicles, considering this characteristic.

Q. Improving handling, noise, and comfort for drivers. It all sounds like you're developing the ideal tire.

That’s correct. We need improvements in all directions, and we develop electric vehicle tires with the highest standards in all categories. All patterns under development should show results closer to the target performances by early 2022.

  • Hankook Tire & Technology-Technology in Motion-EV Tires, Standing at the inflection Point-7
  • Porsche Taycan, High-performance electric sports car with Hankook Tire Ventus S1 evo 3 ev.

Q. Range is still the biggest concern for electric vehicle buyers. Can tires solve this issue?

Increasing the energy efficiency of electric cars is incredibly important, but we cannot solve this issue with only the tires. Reducing rolling resistance can be helpful, but not by much, as the driving distance of the electric vehicle is mainly affected by other external factors. For example, using a heater in winter consumes a lot of the battery, causing the range to drop drastically. In the end, securing a more extended range will likely depend on the battery or charging technologies. Meanwhile, the tire still has a key role to play, so we continue to develop products with a lower rolling resistance and improved aerodynamics that reduce air resistance.

  • Hankook Tire & Technology-Technology in Motion-EV Tires, Standing at the inflection Point-8
  • Audi e-Tron with Ventus S1 evo3

Q. What is the ultimate goal of tire development for electric vehicles?

We analyze data corresponding to the different tires or characteristics per the electric vehicle segments to achieve a competitive development process. We collect digitized and accurate data for every combination of tires and vehicles.

The data collection is being conducted with electric vehicles in the market in the tire development process, which will become more critical in the future. Some car manufacturers only require virtual simulation results without any tire tests carried out by the tire manufacturer. Many companies implement digital simulations using the obtained data to test the vehicles and tires together. As the future electric vehicle launches will utilize this test method, we are heavily investing in accumulating data and improving the data quality.