The NT05 was designed to address the increasing demand for a streetable track tire, one that gives maximum grip without sacrificing wet performance and driveability. The tire's name reflects its place in the Nitto tire family tree. It's the middle sibling between the NT555 ultra-high-performance summer tire and the NT01 competition road race tire. It takes after the NT01 most when it comes to its construction design. One goal was striking a balance between dry handling and wear. This required evaluating and optimizing the three main areas of tire design: construction, tread design, and tread compound.
If you look beneath the rubber, one key feature of the NT05's internal design is two high turn-up polyester plies making up the casing. Instead of stopping at the bottom of the sidewall, the plies continue going down and around the tire's rim bead, with one continuing back to the shoulder block area of the tread. This high turn-up design increases rigidity and stability and adds to durability. Additional features hiding below the tread include a spiral-wound cap ply that maintains the tire's shape under extreme forces, and high-tensile steel belts to optimize handling and stability.
The tread design can be divided in three sections, each with a specific purpose. The wide continuous center rib maintains contact with the road to optimize directional stability and straight-line performance. The large inner and outer shoulder blocks are designed to increase grip and increase stability in corners. To combat wet conditions, two circumferential grooves have been placed to channel water while the 3D tread edges allow the water to drain away from the tread.
Internal construction and tread design are critical, but it's the tread compound that brings it all together. If the compound is too soft, the tire will be sticky but will basically melt and pick up every pebble on the road. If it's too hard, it will make excessive noise and never get sticky enough. Nitto found a compound that was just right by adding one of the key ingredients to carbon black based tread compound-silica. Adding silica to the mix in the right amount gives the tread compound increased flexibility while still maintaining strength at extreme temperatures.
How does silica increase grip? The road's surface may look flat and smooth, but up close it actually resembles something like an English muffin. A standard carbon black compound won't allow the tire to penetrate those nooks and crannies. The increased flexibility of the silica-based compound allows the tread to penetrate surface gaps to increase the tire's bite.
The Nitto team put its test time on the Nrburgring to good use; the NT05 exceeded my expectations in both handling and straight-line performance. Based on initial research, I was concerned with the possibility of increased noise and reduced ride comfort, but these worries were dismissed. It isn't the quietest tire, but quieter that some regular old touring tires I've driven in the past. There was a slight change in the ride comfort compared to the INVO tires I replaced, but it's still better than run-flats.
Instead of the usual press drive, Nitto offered to equip my Mk V GTI project car with a set of NT05s to test. Project GTI makes approximately 290 lb-ft of torque at its wheels, making traction extremely important. To me, a good measure of traction, especially with front-wheel drive, is the tires' ability to reduce the amount of interference from the vehicle's traction control system. The Nitto NT05s have this ability. The company has done an amazing job of adapting the NT01 competition tire into a well-mannered yet aggressive street tire that delivers performance when you need it without constantly reminding you of its track heritage. -Anthony Gelinas
200Traction AA Temperance A