On the skidpad, the NTO5s were given quite a workout. (It should be noted that Gainesville has a 300-foot-diameter skidpad, as opposed to the 200-foot pad we've employed in the past.) Despite having two tons of vintage Tri-Five crushing down on them, we averaged 0.873g clockwise and 0.83 counter-clockwise. Frankly, had the '57 had a shoulder harness or a bucket seat, the CCW number would have been higher, but it was all we could do to stay on top of the bench seat. At least going clockwise we could brace ourselves against the door and keep two hands on the wheel. In the opposite direction I had to brace myself with my right hand on the seat while steering with the left! To put that two-way average in perspective, it's nearly the equal to the new Camaro on 20-inch summer tires, which clocks in at around 0.92g.
In the 420-foot slalom, the NT05s trumped the 555s. We picked up 0.74 mph through the cones (to 42.42 mph), reducing our time from 6.87 seconds to 6.75. The grip was simply outstanding.
More than numbers, however, was the way they felt on the street and during instrumented testing. They responded beautifully to steering inputs and were predictable up to and beyond their limits.
We were not expecting the NT05s to evacuate water the way they did. Their performance in the wet was beyond what we've come to expect from the 555s. Even at speeds approaching 80 mph, the car was glued to the road (no, we don't recommend this). The Bel Air was remarkably sure-footed. Hydroplaning was simply not an issue. The only thing that slowed us down was the 52-year-old wipers. Sometimes they'd work, sometimes not. This is not what we think of when we hear the term "intermittent wipers."
The 555 is still an excellent tire and will offer longer tread life, but for those looking for more aggressive sneakers, Nitto's NT05 might be what you are looking for.