Do bigger wheels reduce EV range? Tyre size, width and rolling resistance explained

Many EVs list a lower official range for the bigger wheel option. It looks odd: the car, battery and motor are the same. The difference comes from the tyres and wheels, and not always for the reason people think.

Where an EV's energy goes at a steady speed

• Air drag: grows with the square of speed, so it dominates on the highway.
• Rolling resistance: the tyre flexing as it rolls and turning energy into heat. It depends on weight and the tyre, not on speed, so it matters most around town.
• Accessories: air-con, heating and electronics.

A tyre and wheel change touches all of these, but by very different amounts.

1. Width: less than you'd expect

Only the bottom part of each front tyre sits out in the airflow. Going 10 mm wider adds only a tiny sliver of frontal area. On a typical sedan at 100 km/h, that alone costs well under 1% of range.

2. Rolling resistance: the big one

Bigger wheel options usually come with sportier, grippier tyres. They have stiffer, softer-compound treads that grip better but waste more energy. Tyres sold in Europe carry a rolling resistance class from A (best) to E, and many Australian tyre shops show it too.

Using our calculator's model of a 1,850 kg sedan, one step worse (class B to C) costs about 5% of range at 100 km/h and about 9% at 50 km/h. Two steps (B to D) costs about 10% on the highway and about 17% around town. That is far more than the extra width or weight.

3. Wheel weight and design

• Bigger alloys and wider tyres are usually heavier. A few kilos per corner matters little at a steady speed, but more in stop-start traffic.
• Open, sporty spoke designs churn more air than the flat aero covers many EVs come with. Taking the covers off can cost a few per cent on the highway.

Before you change tyre size: the rules

The national code for modifying light vehicles (VSB 14, Section LS) sets limits for passenger cars:

• Overall diameter no more than 15 mm larger or 26 mm smaller than a size the maker lists for the model.
• Tyres no more than 30% wider than the maker's widest optional tyre.
• Wheel track no more than 25 mm wider than the maker's maximum.
• Load rating no lower than the tyre placard, and the speedo must stay within Design Rule accuracy.

A larger diameter makes the speedo read low, meaning you go faster than it shows. Your state can add its own rules, and your insurer may want to know. Ask a tyre shop or your state's registration authority before you buy.

Try your own numbers

Our free tyre size and EV range calculator compares two sizes, shows the speedo change and checks the limits above. Buying a used EV on bigger wheels? Factor in tyre costs and range using our used EV checklist.