Nitto maximized the contact...
Nitto maximized the contact patch with a wide, solid patch of rubber running right down the center of the tire. A couple of grooves for D.O.T. compliance help drain water, and wide contact patches on the outside add to the overall contact area.
Whether you have 200 hp or 1,200, you need traction to plant that power and get you going. Generally speaking, the more traction you have, the more power you can utilize, which translates into more fun using your right foot. Today, it's become quite easy to make sick horsepower with your late-model Mustang or fast Ford, and thanks to companies like Nitto Tire, you can put it all to the ground and truly enjoy the fruits of your labor.
It's hard to believe, but it's been 12 years since Nitto released its NT555R drag radial to the public, and high-performance automobiles have been using them ever since to accelerate faster. Recently though, Nitto undertook the challenge of constructing a big brother to the NT555R. Early in 2009, the company released a new ultra-high-performance summer tire, the NT05. Using the NT555R and the NT05 as benchmarks from which to start, Nitto designed a brand new drag radial that's geared towards maximizing traction, while maintaining a stable, high-speed ride down track and/or on the street. That tire is the new NT05R, a D.O.T.-compliant drag radial that features specialized race compound rubber and a larger contact patch for maximum traction.
The 315s are significantly...
The 315s are significantly larger than the 275s that they replaced, and you can also see just how much more solid contact area the NT05R had over the NT555R.
"With the NT555R, we knew it was more street oriented, and decided to come out with something more aggressive," says Nitto technical engineer Alan Ngo. "We wanted to up the performance level and get closer to the other competitors in that segment, and be more comparable to them." Nitto's two main competitors, BFGoodrich and Mickey Thompson, both have products that are known to be stickier and softer than the NT555R, although such attributes come at the expense of durability and streetability, of which the NT555R excels. The new NT05 bridges the gap of streetability with better adhesion, and with that, the softer rubber compound was the major change to the NT05's design versus the NT555R, and offers a zero treadwear rating. As big of a change Nitto made in the compound, the sidewall is considerably important as well.
"There are subtle changes to the sidewall compared to the NT555R, as we had to find a good balance between a soft sidewall that works well at the launch, and a stiff sidewall that provides stability at high speed," says Ngo. Nitto believes it has achieved a very good balance between the compound and the sidewall in the NT05R. Nitto also wanted the NT05R to be legal for use in any drag radial classes, and we think this balance of compound and sidewall will allow them to be used in most sanctions, though we'll have to see what the governing bodies think about it before the 2010 season starts.
Tony Gonyon of TunersInc made...
Tony Gonyon of TunersInc made several baseline runs using the NT555R drag radials that are normally used on the car.
Nitto will have the NT05R available by the time you read this with a roster of seven sizes: P275/40R17, P315/35R17, P285/40R18, P305/45R18, P315/40R18, P345/30R19, and P315/35R20. The 19-inch size will be of particular interest to the Ford GT crowd, as there isn't much in the way of a treaded sticky tire on the market now.
"In the future, we'll be rolling out more sizes, most likely the 15-inch sizes for those who run dedicated drag wheels for the track," remarks Ngo.
With that said, Nitto sent us a pair of the NT05R drag radials for a test session, and to make sure we had something that could take advantage of the new rubber, we lined up a relatively high-horsepower Mustang to give them a workout on the quarter-mile.
We met up with Tony Gonyon of TunersInc (Orange Park, Florida), at Gainesville Raceway in Gainesville, Florida, where he had Jim and Nancy Conners' 2002 Mustang GT. Conners' Colt is a former MM&FF feature vehicle (Sept. '08) that sports a fully built Two-Valve 4.6L mill and a Vortech T-trim supercharger. It puts down 550 rwhp on an everyday, pump-gas tune-up and runs very hard.
To make sure the entire 315mm...
To make sure the entire 315mm swath of rubber met the pavement, we called up American Muscle for a pair of 17x10.5-inch Bullitt-style wheels. The Anthracite finish fit our test vehicle perfectly, and they retail for just $149.99 each.
We began the test with Gonyon making a few runs on the 275/40/17 NT555R drag radials that were already on the car. He started with an 11.21 at 125 mph (1.79 60-foot time) and followed this with an 11.11 at 125.33 (1.77 60-foot). Gonyon has lots of experience on drag radial tires and we felt he was getting as much from the 555s as could be had without spinning excessively. He was launching hard, but wasn't going wide-open on the immediate hit.
With our baseline times on record, it was time to bolt up the NT05R drag radials. Nitto sent us a set of 315/35/17s and we called up American Muscle for a set of its deep-dish 17x10.5 Bullitt-style wheels with an anthracite finish. They looked great against the Mustang's Mineral Gray paint, and the 10.5-inch width allowed the 315 to plant squarely on the pavement. It also fit the SN-95 chassis perfectly and without any modifications.
Gonyon lights up the NT05Rs...
Gonyon lights up the NT05Rs in the burnout box before heading to the starting line. He eventually found that a higher (25 psi) air pressure worked the best.
Airing the tires to 15 psi, Gonyon loaded up and headed to the starting line. Getting acquainted with the tires, Gonyon laid down an 11.09 at 123.97 mph (1.62 60-foot time). On the next pass, Gonyon added 5 pounds of air pressure to the tires, but got out of the throttle down track, as the transmission went into overdrive. Feeling that the tires could use a bit more air pressure, we added 5 more psi for a total of 25. The first 60 feet vanished in 1.59 seconds, and the Mustang crossed the stripe in 10.94 seconds at 124.79 mph.
Feeling the NT05R's were offering plenty of traction, Gonyon made a change to the computer calibration, adding two degrees of timing to get more power from the 4.6L. The Nittos ate up the power and bit hard-Gonyon rocketed to a 10.80 at 125.33 mph (1.60 60-foot). He then backed that up with a near-identical 10.80 at 126.38 (1.60 60-foot time).
At the end of the day, we...
At the end of the day, we dropped a tenth of a second in our 60-foot time, which allowed the car to improve from a 11.11 to a 10.80. Having the extra traction allowed for a more aggressive tune that improved elapsed times as well.
"I was impressed," said Gonyon. "I didn't expect them to perform that well, and I think we could have gone faster-I probably could have gone up more in air pressure, too. The 555Rs are going to be better in the rain and bad weather, but I' rather have the NT05R at the track-most people don't drive cars like these in the wet anyway."
Those that have found the limits of the NT555R will no doubt find the NT05R to be what they need; it should open the eyes of a great many who use other brands as well.