If you're a Tesla owner, you might be wondering — does the size of a wheel really affect the range of an electric vehicle? The short answer is yes, but the degree by which it does might be negligible to some.
Flickr: Ted Eytan
All tires perform the same functions: help (or hinder) vehicle acceleration, braking, steering/handling, and an ability to mitigate shocks and road noise. However, not all tires perform these functions equally, some are rated for higher speeds, others perform better in wet conditions. That said, it's worth discussing the effects that different wheels have on vehicle efficiency and, in turn, range. The general term used to express this disparity in efficiency is rolling resistance.
Rolling resistance, simply put, is the force that impedes motion. The lower the rolling resistance, the higher the efficiency. Several factors cause rolling resistance but a majority of these factors, such as road quality are not within your control. However, one major factor that you can control is the wheel size.
Youtube: E for Electric
Advice regarding wheel size is not as simple as saying that either larger-size or smaller-size wheels are best for every scenario. Both have advantages as well as disadvantages. For example, less power is needed to get a smaller wheel into motion. Therefore, in areas with stop-and-go traffic, it's best to have a smaller-size wheel. When in motion, the vehicle’s motor works harder to cover as much distance as a large wheel. This means larger wheels have more efficiency than smaller wheels when in motion. Check out what happens (see below) when you try to configure the wheels on a Tesla Model X Performance variant.
When you go to select the larger 22-inch wheels instead of the other two wheel options (which are only 20-inches), Tesla informs you that your range will suffer as a result.
Although it was executed for an internal combustion vehicle, a revealing test was conducted back in 2010 by Car and Driver which demonstrated the effects of changing wheel size on a Volkswagen Golf. They tested nearly identical Goodyear Eagle GT tires (from 15 to 19 inches) and analyzed fuel economy variance. What they discovered was that the difference in fuel economy from 15-inch to 19-inch wheels was about 10%.
Thankfully many new electric cars come with wheels that are typically around 18” — so there's room for improvement in range. However, it's likely most drivers would be willing to sacrifice some range so that their Model 3 isn’t running on 15-inch wheels. Additionally, less grip was found on smaller tires, so moving down in tire size is not a simple decision based solely in range — there are other consequences that will impact other aspects of driving.
Looking at Tesla in particular, Troy over at Teslike created a handy table that actually tackles this problem. While literal range tests weren’t performed with every configuration of model and wheel, it was created with several known range calculations and data extrapolated from EPA test results in order to provide a better understanding of what kind of impact different wheels would have on range. The table does seem to align with Car and Driver's findings and what Tesla warns when selecting larger wheels.
While the table only has Model 3 stats, Troy also created tables for the Model S and X on his site. As an aside, you can also see what kind of effect the aero 'hubcap' wheels have on the range. It turns out that these aero wheels only increase range by about 3-4%. Similar results can also be found on a new wheel option that's coming to market soon.
Moving on, there are several tire and wheel packages available from many solid brands. The question is: how can you be sure you're getting the wheel and tire package that will help your electric car perform at its best? Check out this four-step guide to ensure you get the best wheel and tire package:
So yes at the end of the day, the size of your wheel does affect your driving range. But as the EPA states, other key factors impact the efficiency of your car — e.g., aggressive driving patterns with a penchant for high speeds. So when it comes to range, perhaps it's best to make big changes to your personal driving style rather than small changes in wheel size. After all, safe driving can prevent danger and improve range.
An earlier version of this article appeared on EVBite. EVBite is an electric vehicle specific news site dedicated to keeping consumers up-to-date on any developments in the ever-expanding EV landscape.