Engineering Explained uses a lot of math to show electric cars should have fat/tall sidewall tires.
Electric cars are incredibly efficient machines. Jason Fenske once highlighted that his Tesla Model 3 made a 2,000-mile road trip with energy equivalent to one tank of petrol. This is why things that only marginally affect fuel consumption on combustion-engined vehicles have big impacts on EV ranges.
Tyres are a great example, and Fenske did the maths behind them to demonstrate that. If you have an electric car, avoid big rims: fat sidewalls are much better. Don't get us wrong: tyres may also help save fuel, but they are way more important in EVs because of how many miles they can add to the range.
Fenske used Tesla vehicles to make a comparison based on the wheel options they have for a simple reason: it was easier to compare them with official information the manufacturer submits to EPA as a graphic. It shows how much range they have with each set of wheels Tesla sells.
The youtuber checked the range the Tesla Model 3 Performance presents at 75 mph on the graphic with all the wheels it can have. With 18-inch wheels, it could travel 14.9 percent further than the one with 20-inch rims. He also compared the Model S Performance and the Model X Performance in both wheel options they offer, and the result was around 9 percent better with the smaller wheels.
If talking about percentages is not very helpful, know that the mileage difference regarding the Model 3 Performance wheel options is 39 miles. By coincidence, both the Model S and Model X Performance can travel 26 miles more with smaller wheels and taller tyres.
Fenske chose the Performance models because they have more wheel options available. The Model 3 Long Range has only two (18-inch and 19-inch), for example. For bigger differences, he would have to select aftermarket rims and test the cars himself. Since Tesla already did the hard work, it was easier for him to show that the bigger the wheels, the less efficient the electric car will be.
The youtuber also measured the energy requirements a wider tyre presents compared to a narrower one and how rolling resistance influences it. Fenske’s calculations show that the frontal area increase with wider tyres is only slightly higher, but it can represent 1.7 mile less in a trip. That can be the difference between reaching a charging station or calling a tow truck.
When it comes to rolling resistance, an electric car with low resistance tyres can save up to 16 kWh of energy. Translate that into miles, and you could run 53 mi more just by choosing your tyres wisely. Fenske warns tyre rolling resistances are not so big in the real world, but just imagine getting 93.7 miles more of range solely with a wise choice of tyres and wheels.
With this new video, Fenske makes fun of the people who brag about caring for efficiency and the environment. Separating them from those that genuinely do will be easy: just check the wheels and tyres in their EVs. For a matter of coherence, drivers with smaller rims and fatter sidewalls are the real deal.
If you just bought your EV because it accelerates like nothing else, rides on rails, and still saves you money, don’t worry. It is also a perfectly valid reason and still helps keep the air clean, even if a little less. The good thing is that you don’t have to pretend to worry about saving the world while burning rubber with your wide, low profile tyres in good looking rims. Isn’t it liberating?
Source: Engineering Explained