Tire Review: Pirelli Scorpion ATR

photo courteousy Tire Rack

It used to be that if you wanted to use your vehicle off-road, you paid a price: tires that could handle rough or muddy terrain were engineered specifically to do so, and while they'd get you easily through the bush, they were another matter once you got back on the asphalt. The price you paid for off-road performance was a highway ride that was rough, bouncy and very noisy.

Today's trucks and SUVs have an almost seamless ability to go from on- to off-road - in many cases, with a transfer case that engages at the touch of a button - but their tires need to be able to adapt as well. Even if most drivers never go further off-road than missing the driveway and running over the lawn, tire manufacturers have to keep up with the trend.

To that end, I was invited to Las Vegas for the launch of Pirelli's new Scorpion ATR. This new tire will eventually replace the existing Scorpion A/T, which will be phased out entirely once the ATR is up to its full range. Pirelli claims the new Scorpion ATR is equally "at home" both on and off the asphalt, and so we went out to the desert to see.

April can be pretty dreary here in Ontario, and after a long winter, this heat-seeker was looking forward to a couple of days in a nice, dry desert. But a freak weather system brought the temperature down to 4 degrees C - one degree colder than at home! - and dropped hail and sleet on the test track.

It wasn't very pleasant when we were having lunch in an unheated tent, but for assessing the product, it was perfect. Almost any tire can work well under perfect conditions; it's the foul-weather stuff that "makes or breaks" a tire.

Taking the tires through desert outside of Las Vegas. Click image to enlarge

An Escalade with low-profile ATRs in the Valley of Fire. Click image to enlarge

Several SUVs with various sizes and profiles of tires were used; here, a Nissan Pathfinder takes to the trail. Click image to enlarge

We started at the Las Vegas Motor Speedway, where two long lines of SUVs were waiting, all clad in various sizes and profiles of the Scorpion ATR. The tire is available in sizes from 15- to 24-inch, and in P passenger or LT light truck versions; sidewall choices are raised black or raised white outline letters. I chose a Nissan Pathfinder, and headed for the highway to Nevada's Valley of Fire State Park.

Because most SUVs remain on the asphalt, noise was a primary consideration for the ATR. The designers incorporated "sweeping curved" grooves, while the sipes (the fine cuts in the tread blocks) are arranged in a harmonic pattern to absorb noise created by contact with the asphalt.

They certainly did a good job; I found the ATR to be as quiet as most passenger car tires. (My passengers thought so as well; they were tire dealers, brought in from several states for the event, and these guys certainly know their rubber.)

My vehicle's tires were new, but Pirelli claims that the ATR will maintain its all-terrain qualities and still remain quiet when the tire is partly worn.

Once we reached the outskirts of the Valley of Fire, it was time to abandon the blacktop. There are several trails cut across the foothills, and we made our way along one of the rougher ones. The ATR took it on with no problems, but I wasn't surprised; any vehicle, on any tire, can take on a gravel road.

It was when we returned to the Speedway that Pirelli convinced me. An off-road dirt track had been constructed, with the usual ditches, hills and climbs, but the day's precipitation had taken its toll, and the surface was wet, with some goopy areas in the low spots.

For this exercise I chose a Hummer H3, and set out with an instructor and two passengers. The H3 crawled obediently in and out of the trenches, and maintained its grip when teetering sideways with two wheels on an embankment.

But the most compelling test was when I crested a steep hill; on the descent, with the Hummer's nose pointing at the ground, the instructor had me apply the brakes and just sit there for thirty seconds on the wet dirt.

Although the H3 weighs 2,132 kg (4,700 lbs) even before you put four adults into it, it never moved or slid.

From the SUVs, we moved over to a nearby asphalt track, where four vehicles were waiting: two BMW 3 Series and two Minis. All had Pirelli's Eufori@ (yes, I know, but the company says it reflects "technology"; pronounce it like the correct "euphoria") run-flat tires, but on two vehicles, one tire was missing a valve stem and was completely drained of air.

Pirelli mounted Eufori@ run-flats on four vehicles, and on two, removed the valve stems from one tire. Here, a 3 Series tackles the test track. Click image to enlarge

A Mini rounds a sharp turn with one tire flattened, but keeps its grip. Click image to enlarge

Run-flat tires, also known as "extended mobility" or "run-on-flat" tires, use reinforced sidewalls and temperature-resistant rubber compounds that help to maintain integrity when low or deflated. Pirelli says its Eufori@ will do this for up to 150 km, at speeds up to 80 km/h.

There are several benefits, including better control when a tire deflates (a conventional tire will often come right off the rim) and enhanced safety (both in and out of the vehicle; you're not on the side of the highway changing a tire).

As well, automakers can utilize the space normally occupied by a spare tire for extra cargo room, and there is a weight savings when an extra tire and rim are eliminated.

On the down side, run-flats are more expensive than conventional tires, and require special rims and tire pressure monitoring systems (TPMS), since they don't look any different when they deflate and the driver must be informed of air loss via a dash-mounted warning.

Because of these factors, they're almost exclusively sold as replacements for original equipment, rather than drivers swapping them for conventional tires, but when TPMS becomes mandatory on all vehicles in the 2007 model year, expect to see tire manufacturers emphasizing the safety factor as they try to get drivers to switch.

Currently, they're mostly found on premium vehicles; BMW now uses them on all 3 Series models (except for the M3) and on some 5 Series models, and expects to broaden the range in future generations of the 7 Series, X3 and X5.

Our task was to take the vehicles through hard acceleration, panic stops, sharp turns and slaloms, and figure out which tire was flat. There were no visual clues: all four looked equally inflated.

I was expecting some deterioration in handling, especially since I tossed the cars quite hard into the curves, but there was none. Only on hard braking, when the steering wheel moved slightly to the right, was I able to confidently determine which tire was faulty.

Because of their beefed-up construction, run-flats are notorious for giving a much firmer ride than conventional tires; a Pirelli spokesman said the Eufori@ gives a comfortable ride, and in future I'm going to try to score a vehicle so equipped and give it a shakedown on the street, since our short track test didn't really give much time to focus on that aspect.

An Expedition at the lookout point. The Scorpion ATR is original equipment on some Ford vehicles. Click image to enlarge
It's easy to say nice things about a product when you're the company's guest, but I'm not falling into that trap; the Scorpion ATR and Eufori@ impressed on their own merits. Most SUV owners will never drive anywhere other than the street.

So the ATR's off-road ruggedness may be lost on them, but its ability to hold a heavy vehicle on a muddy hill should translate well into sure-footedness in nasty weather (the Scorpion ATR is offered as original equipment on a few vehicles, including the Ford F-150). And while tires overall have improved in quality, with blow-outs now much rarer than they used to be, the Eufori@'s ability to maintain control even in extreme conditions should give drivers extra peace of mind.

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