To evaluate the tires, we recorded lap times around Tire Rack’s on-site track that combines a short slalom, three 90-degree right-handers, and two larger curves. The loop is relatively tight without elevation change, emulating an autocross course more so than a road course. Just fifty feet from the warehouse where hundreds of thousands of tires are stored, the track allows Tire Rack product experts to explore at-the-limit handling and transitions between braking, accelerating, and cornering, so they know the products they’re selling.
We have measured brake distances from 50 mph and captured left and right lateral acceleration on a 200 leg skid pad. Because you can’t fit a spare set of tires in the Miata’s trunk, we’ll be driving our new performance tires on public roads every time we go the track. To that end, we added a 6.6-mile road loop to evaluate ride quality and tire noise.
Yokohama Advan A11ABraking distance: 85.1 feetSkidpad, L/R: 0.93/0.90 gLap time: 30.680 secAs we documented in new update, driving on Miata quickly requires patience, confidence, and experience. The ample body roll and squishy tires mean that the car doesn’t settle into a curve until long after the initial turn-in. We’re reminded of that as we hurry through the slalom and roll through the short, sharp corners.
The course is so tight that the Miata does not have the opportunity settle on to compress spring and tire in the turns. On the road, our Miata on stock tire toward comfort rather than sport, softly soaking up bumps. The ride is never jarring and sometimes even borders on being too gentle, oscillating over expansion joints where we’d prefer more direct damping. We hope stiffer tires eliminate that behavior by removing some of the compliance from the suspension system.
Dunlop Direzza Sport Z1 Star SpecBraking distance: 79.9 feetSkidpad, L/R: 1.00/0.96 gLap time: 30.123 secFitting on our first set of performance tires utterly blows us away. We didn’t think tires would have such a significant effect in stabilizing the Miata’s roll in turns. The Dunlops completely transform the Miata, improving driver confidence and measurable performance in every test. The steering weights up earlier and becomes much more responsive on-center. (We were already quite pleased with the steering on stock tires, so we were delighted that it got even better).
Turn-in is more than immediate, it’s almost preemptive. Shod with Direzzas, the Miata changes directions just as quickly as your brain orders the command. On city streets and highways, the ride is more direct, but it isn’t punishing or harsh. The Dunlops deliver the perfect damping and sportier ride that we had expected from our Miata when it arrived on day one. The only real negative with these tires? There is a touch more road noise audible through our factory hardtop above 50 mph.
Hankook Ventus R-S3 Z222Braking distance: 77.3 feetSkidpad, L/R: 1.03/0.98 gLap time: 29.998 secThe Hankooks have phenomenal lateral grip and deliver the quickest lap time and the highest skidpad grip. Turn-in isn’t as immediate as with the Dunlops, but there is a significant improvement over the stock Yokohamas. For all of the stick they have in turns though, the Ventus doesn’t have the same confidence under braking. Yes, they delivered the shortest stopping distance, but the tires aren’t quite in sync with the antilock brake calibration.
This could be unsettling on the handling loop. There’s also no question that the Ventus are the most compromised of all four tires when it comes to on-road civility. The Hankooks read road imperfections very literally, tramlining a bit and conveying every small joint in the pavement to the driver’s rear end, and they’re also the loudest of this group. They aren’t offensive during our 6.6-mile drive, but they would likely get tiring on the three-hour slog to GingerMan.
Bridgestone Potenza RE-11Braking distance: 81.6 feetSkidpad, L/R: 0.98/0.92 gLap time: 30.430Just like the Hankooks and the Dunlops, the Bridgestone are clearly superior to the Yokohamas in handling. Rather than the two-part compression of the suspension and then the tire, the Potenzas are firm enough that the Miata is poised from the moment the body leans onto the outside springs.
However, these tires don’t feel like they’re following the driver and the car quite like the other two aftermarket tires. In all three measured tests, the Potenzas were an improvement over the Advans but slower than both the Ventus and the Direzzas. As a consolation prize, the Bridgestones took the top honor in our subjective on-road test. The firmer and shorter sidewalls eliminate the bounce of the stock tires, and they’re actually quieter.
Making the decisionIf we were simply reading the data, we would have been riding home on the Hankooks, but that’s not the case. Automobile Magazine has never been all about the numbers; we place a lot of value on the subjective feel of a car or, in this case, the tires. All three tires showed empirical improvement in braking, lateral grip, and lap times, but the real story is the dramatic transformation they had in chassis composure and cornering confidence.
Based on our time behind the wheel, the Dunlops delivered the most assurance and predictability — a very valuable attribute when drivers of such varying skill are driving on a track. The Dunlops truly transform the Miata’s steering. And while the difference in on-road behavior between the Hankooks and Dunlops isn’t significant, we can say that our Direzzas are quieter and ride a bit better than the Ventus. That’s how we ended up with four new Dunlop Direzza Sport Z1 Star Specs. Now we can’t wait to get back to GingerMan Raceway to experience the Miata on a true road course with its new tires.
Wedclix - Get Automotive Review & Wiring Diagram Library
Copyright © 2003 - 2018 Domain Media. All sponsored products, company names, brand names, trademarks and logos arethe property of their respective owners.