Stopping Distance and Grip With 18- and 19-inch Tires - 2017 Tesla Model 3 Long-Term Road Test

2017 Tesla Model 3 Long-Term Road Test

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2017 Tesla Model 3: Stopping Distance and Grip With 18- and 19-inch Tires

by Dan Edmunds, Director of Vehicle Testing

You've probably heard the recent news that Consumer Reports tested its Tesla Model 3 and proclaimed it severely lacking in the brake department. This was based in large part on a 152-foot result it reported after conducting a series of 60-0 mph panic stops. We don't know the ins and outs of CR's test procedure or the condition and texture of the asphalt at its test facility in Connecticut. What we do know is that, like us, Consumer Reports privately bought its test car; it's no press loaner. Its car also has the standard 18-inch wheels and tires that we bought.

CR's ghastly result was a big surprise to us. We recorded a fairly normal 60-0 mph panic-stop distance of 133 feet when we tested our 2017 Tesla Model 3 on our own test track. While our result is perhaps a few feet longer than we typically see on mass-market cars with all-season tires, it's fairly typical of hybrids and electric vehicles fitted with low-rolling-resistance tires designed for maximum range and efficiency. Mildly disappointing, but not headline-worthy.

Our testing program does not stop at braking, if you'll pardon the pun. Our Tesla Model 3 accelerated to 60 mph in 5.3 seconds, and it produced a respectable 0.85g of grip when orbiting our skidpad. We also feel out a car's handling by lapping it around our test track, and here the Model 3's front end displayed mediocre grip when entering corners, followed by subtle yet persistent traction control interventions on the way out.

This wasn't viewed as a huge liability, though, because a) it's natural to push a car harder on a closed track and b) no one — myself included — thought ill of the Model 3's brakes or handling after driving it on their favorite mountain road.

Still, the full-ABS stopping distance and the iffy track grip made us wonder about the optional 19-inch tires. Should we have bought them? Are they worth the $1,500 price tag? To find out, we borrowed a set and headed back to the track to repeat our tests.

The standard 18-inch bits fitted to our car (and CR's) are 235/45R18 Michelin Primacy MXM4 tires mounted on aluminum alloys covered by aerodynamic snap-on plastic wheel covers. The optional 19-inch setup consists of uncovered aluminum alloys wrapped with Continental ProContact RX tires in size 235/40R19.

You'll notice that both have the same tread width of 235 mm, so the 19-inch tires are no wider. Also, both are all-season tires, so there's no difference there. But there was still reason to proceed since the 18-inch Michelins have a treadwear rating of 500, which suggests a harder tread than the 19-inch Contis and their 400-rated tread. In addition, Tesla recommends 45 psi for the 18-inch Michelins but 42 psi for the 19-inch Contis.

This is odd. The 18-inch tires have a higher load rating in keeping with their taller sidewall and larger air volume, so they shouldn't need extra air to support the car. Tesla's higher air pressure specification seems expressly intended to reduce the footprint of the tire to improve rolling resistance and maximize EPA-rated range and consumption.

These facts made it seem likely that the 19-inch tires would outperform the standard 18-inch tires, but testing was the only way we could confirm this theory and see if the measured difference — if any — was worth it.

The difference was bigger and broader than expected. The 19-inch Continental tires made our Model 3 launch more smartly to produce a better 0-60 mph acceleration time (5.1 seconds instead of 5.3), stop shorter from 60 mph (128 feet instead of 133), and generate a lot more grip around the skidpad (0.93g instead of 0.85g).

Beyond the numbers, this simple tire change absolutely woke up the Model 3 on the handling circuit, where all of the above objective data points came together to produce a more engaging driving experience. It turned into bends more precisely, hung on through corners more tenaciously, and allowed the driver to roll onto the throttle with more authority on the way out.

In short, the 19s made our 2017 Tesla Model 3 a lot more fun, and by a considerable margin. But this was more than a performance and fun-to-drive upgrade. A shorter panic stop can reduce the likelihood or severity of a rear-end collision. Sharper track handling reflexes also translate into better accident avoidance on the street. And we also found that ride comfort and road noise — attributes seemingly unrelated to tire grip — improved considerably.

2017 Tesla Model 3

Grippier tires could be expected to worsen consumption and range, but we didn't see any measurable ill effects. The tire break-in period included a 400-mile road trip that seemed as normal as any other we've taken. We can't say for certain that there are no losses on this front, but we can say that the benefits are far more obvious and clearer than any imagined drawbacks.

All of this got me thinking about a career I had before coming to Edmunds. I used to tune the suspension and tire packages of prototype vehicles, and our results lead me to believe that the Model 3's optional 19-inch tire may well have been the reference tire used by Tesla engineers when they tuned the suspension and the ABS and traction control systems.

Not only does the car objectively perform better and stop shorter, it generally feels more agreeable and pleasant to drive in a wider range of conditions. Whether that theory is true or not, I can say the $1,500 for the optional 19-inch Continentals is money well spent.

That said, the Continentals are still all-season tires. Our 19-inch retest suggests the Model 3 chassis has even more to offer. If performance is truly all you care about, and you are willing to sacrifice some range and flirt with the idea of swapping tires in winter (assuming you live where that's even a thing), your best option might be to order your Model 3 with the 18-inch Michelins. And then use the $1,500 you save to offset the cost of aftermarket wheels and stickier tires of your own choosing.

If that's not you, configure your Model 3 with the 19-inch Continentals. I sure wish we had.

Dan Edmunds, director of vehicle testing @ 5,502 miles

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