4 ms·

> are smaller wheels Looks like rolling resistance decreases with diameter [1]. So, is it from the increased drag from higher stance? Would lowering the car th

• mortos 9mo ago
  I think it's mostly from aerodynamics. Lowering the car could help but even just smaller rims, with the same overall diameter (rim + tire), can have a 15% impact on range. This Engineering Explained[1] video does an okay job with some of the math but he clarifies it well with a comment: > CLARIFICATION! Why do bigger wheels mean worse efficiency, when the overall tire diameter remains the same? This comes down to aerodynamics. A 20" wheel will cause more of a disruption in airflow than an 18" wheel. That's why Tesla (and others) uses aero covers on their wheels (Car & Driver testing showed it gives about a 3% efficiency bonus at speed). The smaller the wheel, the more of the side profile of the wheel & tire is perfectly flat (the tire is flat, the wheel open: more tire = more flat area, less open area). Ideally, you'd have just a plain, solid sheet for the wheel, but obviously that's not idea for brake cooling. Wheel covers are today's common compromise as they have some airflow, but minimal. [1] https://youtu.be/NYvKxsYFqO8 https://youtu.be/NYvKxsYFqO8
  • nomel 9mo ago
    > solid sheet for the wheel, but obviously that's not idea for brake cooling So, temperature driven radial louvers!? :D