Can EV-Specific Tires Help Make Up For Range Loss Over Time?

We test ERange tires on my 2013 Ford C-Max Energi PHEV to help find out.

Michael Bettencourt is a long-time EV owner, both of BEV and PHEV vehicles, and automotive journalist whose vehicle reviews have specialized in EVs and plug-in hybrids for the past 10 years. We’re following Michael in a new series about the experience of EV ownership, in the short and long term. 

Battery degradation is a cruel but inescapable reality for EV drivers, even if EV owner-based empirical data suggests that this degradation is not nearly as extreme as many (less informed) EV critics suggest. Automakers battery lifespan estimates of 15 to 20 years looking fairly realistic – and possibly longer, depending on mileage, plus how they’re used and cared for, of course.

After buying our family’s first EV in December 2011, our trusty but oh-so-early 2012 Nissan Leaf, we traded it in for a slightly newer 2013 Ford C-Max Energi in summer 2016. Thus banishing EV range anxiety – especially in our cold northern winters in Toronto – from our daily commuting lives.

Or so we thought.

As the years since have passed, we’ve found that daily charging does not provide quite the same all-electric range as our C-Max Energi used to offer. So I looked forward to trying these new highly-hyped ERange tires designed specifically for EVs as soon as they became available.

That day came yesterday, as I write this, and I’m looking forward over the next few weeks to tell you how it’s going with them, plus go into more depth on the trials and tribulations of long-term EV ownership, while updating my observed range figures over these first few weeks of summer.

Granted, our Ford PHEV’s e-range wasn’t huge to start: the EPA figure for a new ‘13 C-Max Energi came in at just 19 miles of all-electric range. That was just enough to cover my wife’s daily commute in moderate, non-winter temperatures at the time we acquired it – barely, but it covered.

This is sadly not the case anymore. And when the serenely refined electric range is done, the 2.0-litre 4-cylinder Atkinson engine loudly announces it’s back on the scene, seemingly trumpeted even louder by a continuously variable transmission that plays a buzzy duet that transforms – some might say ruins – the fairly advanced drivetrain feel of the entire package when in EV-only mode.

This golden silence and relative cacophony when it ends makes every mile of all-electric range extracted from our C-Max Energi precious to the driver. Though significant gas savings and emissions reductions are nice bonuses here too.

ERange tires can help extend range, as can warmer weather, but by how much?

On an earlier preview test of a Tesla Model 3 on a set of ERange tires in and around Los Angeles, after a full day of mixed driving, I found efficiency numbers that lent worthy real-world data points to support the company’s estimate of a seven percent improvement on the Model 3’s official EPA combined figures. It was far from a scientifically-controlled test, but in my morning stint, there was a meager 1.2-percent improvement, but then a whopping 11.5-percent improvement to 4.34 miles/kWh on my longer and more varied afternoon drive, compared to the Model 3 LR’s official 3.8 miles/kWh. 

Did the folks at Sailun somehow manage to find a route that included city, highway and canyon driving that afternoon that was all downhill?

For us, a 7-percent improvement in our electric range would be much less dramatic – at roughly 1.33 miles if it still offered the full 19 mile range as new (which it doesn’t) – but would provide back some of the precious EV range we lost to degradation over the years.

So how much of that battery degradation EV range could be recouped? I couldn’t wait to try them out on our own C-Max to try to find out.

First ERange test versus my three-year-old all-season tires

My local tire shop recommended an alignment as soon as I told them of my plan to do a careful EV-mode range comparison of my current all-season tires versus the exact same route on the ERange tires.

My current tires were three year-old Toyo Extensa A/S II all-seasons, a low-cost tire designed for long tread life more than anything else, and are not low-rolling resistance like the ERange. Since I also had swapped out those Toyos for winter tires, the Toyos were running on roughly 18,000 miles worth of tread wear, or roughly a quarter of the way through their tread life.

All the tires were the same 225/50R17 V-rated rubber as the stock size, even though the factory rims are now mounted on my winters. I planned out a test route of 19 miles that started right after a full charge at the L2 in my garage, with a 50/50 mix of city and highway driving, using the EV Now mode that keeps the Ford using electrons unless you stomp on it, and climate control off the entire way.

No A/C was a challenge in stuffy conditions that ranged from mid-to-high 70s and high humidity throughout, so in the city, the windows were mostly down. Trying to maintain as similar acceleration as possible throughout was also a challenge, so I tried to drive normal up to each road’s speed limit (20-40 mph in town, around 60 on the highway), although needing to prevent the engine from turning on even in EV Now mode meant I was gentler on the accelerator than I normally would be – or any time-conscious drivers.

My first test-run was done pre-alignment, where I hit 15.4 miles, suggesting I was now working with about 81 percent of the CME’s original 19 miles of all-electric EPA range. I also went to a public FLO L2 charger soon after, leaving it there for over three hours to ensure ample time for a full drink of electrons, with the total energy replenished coming out to 4.9284 kWh. This from the CME’s liquid-cooled 7.6 kWh battery pack, which when new, offered 7.2 kWh of usable energy.

This smart FLO’s meter therefore suggested my plug-in hybrid battery’s usable capacity had diminished to a sobering 68.5 percent of its original usable capacity over its 10-year lifespan. For the record, my C-Max Energi has traveled a total of 92,239 miles, of which 48,125 miles of those were on battery power, according to the dash’s most recent Lifetime Summary pictured here.

So almost exactly half of its total use has been running electric. Which may be a philosophical gut punch to the BEV-angelists that declare all PHEV owners rarely if ever plug in their vehicles, and don’t want to classify plug-in hybrids as EVs at all. Our total proportion of EV use could have been even higher, as it had been leased for three years before we received it, where the CME’s lifetime summary then had been closer to a 60/40 gas/electric ratio when we first acquired it.

The prior owner had plugged in regularly, but had driven more than our urban family’s usual 10,000-ish mile yearly total.

Initial verdict on all-season versus ERange tire tests

After a full charge in the C-Max, the dash usually shows 16 miles of total range available, which I’ve found to be fairly accurate in these carefully driven tests. After the alignment, with air pressures all set to factory 36 psi recommendations, my three-year-old all-seasons ran on a full charge for 15.7 miles, a very slight improvement over their pre-alignment figure. I quickly pulled into a nearby gas station to take note of this, and to help keep in mind the physical point at which the EV range ended.

It was then back to the tire place for a quick tire switch, then back home for a full charge for 2.5 hours before doing the same loop on the ERange tires. Within 0.1 of a mile of leaving home, the range estimator jumped up from the usual 16-mile EV range estimate up to a surprising 18 miles. Okay, two extra miles doesn’t seem shocking, but that would constitute a healthy 10.5 percent increase, although the quickness of its addition had me thinking that the Ford’s computer had simply adjusted to my more conservative ‘test mode’ driving style.

Which seems to be the case, as by the turnaround point in the route, the remaining range was at nine instead of eight miles previously. And by the end of the test, the range ended at a somewhat disappointing 15.2 miles before the engine kicked in, or roughly the same EV range as on the all-season tires, pre-alignment.

Wait a minute, what happened? I realized that by the time the car finished charging, I had missed much of the rush-hour traffic I had hit on part of the highway stretch in my aligned all-season tire test, and on the earlier one as well. So I took the Ford through the same route again the next day closer to the original rush hour time frame – traffic is never exactly the same density day after day, but traffic patterns are patterns for a reason. And voila: a healthy 16.9 miles of all EV range! Marking an extra 1.2 miles on the ERange tires over the aligned all-season tires, which represented an increase of roughly 7.4 percent of the CME’s all-electric range.

The extra braking of stopped or slower highway traffic and less high-speed proportion of miles helped extend out the battery range. I estimated my planned 50/50 proportion of city/highway driving ratio would be closer to 60/40 if you count the time slowed by in-town-like highway congestion.

Clearly, this is another interesting data point, not a proper scientific test, which would be impossible to perform on public roads due to all the variables. But it’s more illuminating in a pattern that suggests the company’s estimates on the effects of the ERange tires on electric range are certainly worthwhile, and measurable, if variable due to driving conditions – as always, YMMV.