New Car Reviews

2015 Jaguar F-Type S Coupe – How Do Worn Tires Affect Performance?

Miles to Date: 23,145

Long-Term 2015 Jaguar F-Type Update: Spring 2015 ( 1 of 2 ) Miles to date: 23,145

One look at the summer tires on our Four Seasons 2015 Jaguar F-Type was all the evidence we needed that our colleagues in Los Angeles had their fun while the car was stationed in Southern California. The rear tires were almost totally worn out, even though they had only covered about 15,000 miles. We knew we needed some fresh rubber for summer in Michigan, but we also were curious how much the beat-up tread was hindering our F-Type’s performance. To find out, we asked Tire Rack, our official wheel and tire supplier, for some input.

Woody Rogers, product information specialist at Tire Rack, meets us at the company’s headquarters in South Bend, Indiana, to help us understand how tire wear affects grip. Surprisingly, Rogers says that worn tires actually have similar grip to new ones in the dry. In fact, the smaller tread blocks of partially worn tires “squirm” and flex less under hard cornering or braking, making them feel more precise. Instead, most drivers only notice their tires are worn when they find the tires no longer grip as well in the wet, he says. Worn tires still tend to be louder and less comfortable on dry roads.
To get a baseline impression of the Jaguar’s used rubber, Rogers and I take the F-Type out on Tire Rack’s 6-mile public-road evaluation loop. Rogers knows these roads so well that he has very specific directions for driving them — 38 mph on this stretch, stay near the white line here to hit the most broken asphalt — and he helps me listen and feel for how the tires cope with different types of pavement.

“A tire that makes a lot of impact noise doesn’t necessarily ride stiff,” he cautions. “Excessive tire noise can often lead people to think their tires ride harsher. I literally plug my ears [to judge ride quality]. I want to take the sound out of the equation.”
Unfortunately for us, we find that the worn Pirelli P Zero tires on the 2015 Jaguar F-Type both roar and feel stiff and choppy over broken roads. Sure, the F-Type is a loud, taut-feeling sports coupe, but I’m hopeful fresh Pirellis will soften and quiet the car for my drive home.

On the track

Next, we move to Tire Rack’s handling track, where the company usually uses a fleet of BMW 3 Series test cars to evaluate tire performance on a tight, technical autocross course. Rogers straps in a Race Technology DL1 data
logger, and I strap in for some laps. After some coaching from Rogers, who has run this course literally thousands of times, I post a best lap time of 31.72 seconds. The F-Type is huge fun out here, exhausts crackling and rear end stepping out easily if you’re too aggressive on the throttle. I swap seats with Rogers, and he lays down a 29.80-second lap. It’s his first time driving an F-Type, and he’s very pleased with the car’s straight-line power and eager turn-in. He’s also impressed with how well the Jaguar’s brakes held up to our abuse: “It feels like it’s hardly working. A typical street car, it would all be overheating after that many laps out here.”

The big takeaway from our track session is that the thoroughly worn Pirelli P Zero tires actually still provide a good amount of grip; Rogers says a 29-second lap is about what he’d expect a 3 Series with fresh high-performance tires, so we haven’t lost that much traction as the tires wore down. But the tires are very peaky in their performance; when you push for just a little bit more grip around a turn, the tires very quickly break away and start sliding. That’s not a trait that Rogers or other Tire Rack employees like in tires for street cars, as the sudden handling changes could surprise a driver.
“I’d give up a little grip to gain predictably and controllability,” Rogers concludes.

In the shop

We park the 2015 Jaguar F-Type inside Tire Rack’s workshop, where several members of the public are also having tires changed on their cars. As technician Jeff Rose jacks up our car and begins pulling off the old tires, we get a chance to see how 15,000-mile and 0-mile Pirelli P Zeros compare. Not only do the old tires have far less tread overall, but some of the sideways grooves in the tread blocks that would push water or gravel out of the tire’s path have been totally obliterated as the tire wore.
The old tires have roughly 3/32nds of an inch of tread left, which Rogers cautions is about the limit for driving them in the wet. I admit that I drove through a downpour on the way here.

“Driving [a tire] down to 2/32nds of tread is fine” in the dry, he says. “If you’re going to encounter rain, you should be shopping for new tires at 4/32nds.”
Rose fits the new tires to the Jaguar’s 19-inch wheels, runs them on the high-speed balancer, gets them back on the car, and we’re good to go. A new set of Pirelli P Zero tires will take a big chunk out of your wallet. Our tires (in sizes 245/40/R19 front and 275/35/R19 rear) cost $1,190 before taxes and installation. Add those in, and the entire invoice comes to $1,334.30.

Much more comfortable on the road…

I steer the F-Type back out onto the Tire Rack road-evaluation loop, and even my untrained butt and ears detect differences in how the new tires perform. For one, the initial impacts over highway expansion joints are a little more muted. The car’s still on the rigid side, thanks to its sporty suspension, but the hits over bad pavement are definitely mollified. There’s also less tire roar, especially on concrete surfaces. The difference is mostly because the new tires have taller, squishier tread blocks that can flex and move a little more.

…but what about at the limit?

It’s on the track that I’m expecting more significant differences, and for my first few laps I noticed we have significantly less grip than before. Testing tires so soon after fitting them isn’t ideal because it generally takes 100 to 200 miles to use up the mold-release compound on the outside of new tires. Manufacturers coat the insides of their molds with a special nonstick spray — think of it as Crisco for tires — and some of that low-grip material remains on the outside of new tires. Hard braking now activates the ABS much sooner, I can’t push through corners as fast before the front end starts to slide wide, and the Jaguar takes a split-second longer to change direction through the slalom.
Soon, though, the tires warm up and start to grip as well as the used ones. I start to turn in quicker and quicker lap times, and I begin to appreciate that the slightly bigger, squishier tread blocks are more forgiving. I can feel the car shift its weight and ready itself on the flexing tires before reaching the limits of grip, and it’s easier to tell how hard I’m pushing my luck. Quickest lap time: 31.24 seconds, fractionally faster than on the old tires.

Rogers takes the helm and, too, prefers that there’s a little more compliance at the edge of the tires’ grip. He likens the tires’ performance to the top of a mountain: The old Pirellis were a sharp peak that instantly fell off, but the new ones are more like a plateau of grip that give you more compliance as you approach the limit. It all comes down to trading maximum traction for predictability.
“I like this one a lot more,” Rogers says of the fresh set of tires, “But it does not seem to have quite the braking traction of the other one. If I had to go qualify on one of them, I’d want the other one [the worn tires]. If I had to go run a long stint, I’d want these ones.”
His quickest time on the new tires is 29.90 seconds, a negligible 0.10 second slower than our morning session.

What’s shakin’?

I’m ready to make the three-and-a-half-hour drive home, but only 5 miles along U.S. 31, I notice something’s amiss. The steering wheel is shaking back and forth, and there’s an unsettling vibration from the Jag’s tires. Didn’t I watch Jeff Rose run each of the wheels and tires on a balance machine before he put them on the F-Type?
I head back into Tire Rack’s service bays, and soon enough we have an answer. All that hard braking and acceleration on the company’s handling track caused the tires to “slip” on the wheels. They’re rotated out of position, shifting the weight distribution of the rubber relative to the wheel out of balance. Rogers explains that a lubricant used to help technicians fit tires onto wheels takes a few days to dry and that you should drive gently on new tires. In other words, if you’re buying a new set of a track-day tires, put them on at least a week ahead of your event.

“I would blame it wholly on the driving we did,” Rogers says of our misbalance. “We don’t encourage someone to go right to the track.”
Oops. Sports car owners, learn from our mistake.
Soon enough I’m back on my way, wheels perfectly balanced and tires humming along the highway. Now that I’ve had a taste of the F-Type’s handling chops, though, I’m starting to figure out when I can next take the car to a track to properly break in the new rubber. Time to sign the 2015 Jaguar F-Type S Coupe up for a day at Michigan’s Grattan Raceway.


 

Overview

  • Body style 2-door coupe
  • Accommodation 2-passenger
  • Construction Aluminum unibody
  • Base price (with dest.) $77,925
  • As tested $92,575

Powertrain

  • Engine 24-valve DOHC supercharged V-6
  • Displacement 3.0 liters (183 cu in)
  • Power 380 hp @ 6500 rpm
  • Torque 339 lb-ft @ 3500-5000 rpm
  • Transmission 8-speed automatic
  • Drive Rear-wheel
  • EPA Fuel Economy 19/27/22 (city/hwy/combined)

Chassis

  • Steering Electrically assisted
  • Lock-to-lock 2.5 turns
  • Turning circle 35.8 ft
  • Suspension, Front Control arms, coil springs
  • Suspension, Rear Control arms, coil springs
  • Brakes F/R Vented discs
  • Wheels 19-inch aluminum
  • Tires Pirelli P Zero
  • Tire size 245/40R-19 (94Y), 275/35R-19 (96Y)

Measurements

  • Headroom F/R 37.0 in
  • Legroom F/R 43.0 in
  • Shoulder room F/R 56.5 in
  • Wheelbase 103.2 in
  • Track F/R 62.8/64.9 in
  • L x W x H 176.0 x 75.7 x 51.5 in
  • Passenger capacity 51.9 cu ft
  • Cargo capacity 11.0 cu ft
  • Weight 3514 lb (est.)
  • Weight dist. F/R 50.0/50.0% (est.)
  • Fuel capacity 19.0 gal
  • Est. fuel range 410 miles
  • Fuel grade 91 octane (premium)

Equipment

  • standard equipment

    • Adaptive suspension
    • Active exhaust
    • Limited slip differential
    • High-performance braking system
    • Dynamic and winter driving modes
    • Xenon headlights
    • Dynamic stability control
    • Meridian surround-sound audio system
    • Keyless entry and ignition
    • Bluetooth audio and phone connectivity
    • Sport seats
    • 6-way power seats
    • Navigation
    • Remote hatch release

Options

  • options for this vehicle:

    • Performance package S- $3400
    • Performance seats
    • Configurable dynamic mode
    • Super performance brakes w/red calipers
    • Flat-bottomed steering wheel
    • Selectable active exhaust
    • Interior black pack
    • Extended leather package- $2700
    • Vision package two- $2400
    • Adaptive and intelligent front lighting
    • Front parking assist
    • Rearview camera
    • Blind spot monitoring system
    • Premium package two- $1800
    • 14-way power seats
    • Automatic dual-zone climate control
    • Homelink
    • 19-inch black Centrifuge aluminum wheels- $1500
    • Panoramic glass roof- $1200
    • Rhodium Silver metallic paint- $600
    • Climate package w/heated seats and steering wheel- $600
    • HD radio and SiriusXM satellite radio w/trial subscription- $450