Yahoo Autos Quick Tire Test: Dunlop Direzza "Star Spec"
Welcome to Quick Tire Test. In this feature, we'll be taking a look at some popular (and some not-so-popular) tires aimed at the auto enthusiast by testing them under real-world conditions Whether it's the top-shelf track superstars or the affordable-value diamonds in the rough, we will give you an idea of what to expect-and what you didn't expect-from each.
Tire Name: Dunlop Direzza ZII Star Spec
Size Tested: 225/45R17
Primary Testing Venue: American Endurance Racing at Mid-Ohio
Vehicle Used: Mazda MX-5 Cup Car (NC generation)
What Is It? When the SCCA opened up the Street Touring autocross classes more than a decade ago, they stoked some real interest in the idea of tires that offered a 180 or 200 treadwear rating while providing grip that was close to 50-treadwear "R compound" tires like the Hoosier R6, Toyo R888, or Michelin Pilot Sport Cup. The arrival of competition-oriented street-tire endurance races like ChumpCar, WRL, and AER fanned that flame into a veritable forest fire, aided further by the SCCA's decision to mandate 200-treadwear tires for Street classes.
Dunlop's first effort at this market, the Direzza, spawned the cult-classic Z1 "Star Spec." The ZII that followed in 2013 was a faster, better tire, but it also caused a collective holding of breath among the enduro-race community. The release of the ZII Star Spec means that everybody can whoosh a bit with relief. Testing by the Tire Rack has shown this tire to be faster in autocross situations than all previous Direzzas.
What's It Good At? We had high hopes for the ZII Star Spec when we mounted a set to our MX-5 Cup Car for a double nine-hour enduro at Mid-Ohio with American Endurance Racing. Those hopes were entirely realized; we ran as high as second place on Day One and led much of the race on Day Two. Although we had mechanical issues that prevented us from a podium both days, the performance of the Dunlops was beyond criticism. And after about thirteen hours of hard use, visible wear was pretty much limited to the outside blocks of the front tires.
What Wouldn't You Expect? By definition, these "extreme performance" tires are optimized for hot conditions. So when we realized that both of our races would start in near-freezing temps-35 degrees Fahrenheit on Saturday and 36 degrees Fahrenheit on Sunday-we had concerns about having enough grip to get through the first few hours. We needn't have worried. There was adequate grip on offer early in the morning and by the time the thermometer hit 40 and the tires were scrubbed in we were able to get within a few tenths of our best lap times.
What Would You Change? We saw a little bit of unexpected fluctuation in tire pressures during the race. In particular, the rear tires had trouble coming up to the temperature and pressure we wanted. But much of that can be attributed to the MX-5's light weight. This is a tire size that can find applications on everything from GTIs to fourth-gen Camaros, after all.
Anything else? It should be mentioned that these tires are some of the more affordable entries in the segment, particularly considering that they are made in Japan rather than in a low-cost country like China or Indonesia.
What's the overall story? As competition tires, the Direzzas are brilliant. They'd be a great choice for anybody looking to add some grip to their current car. Just be aware that they aren't meant to run in the winter, and they aren't meant to last forever. We're looking forward to getting a few more great races out of these.
Dunlop provided two sets of tires to complete this test. - Ed.
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