Andy Hollis
Andy Hollis
7/12/18 10:21 a.m.


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Spring is in the air. Temperatures are warming, flowers are blooming, and this year’s crop of new tires is hitting the shelves. This is the time when tire makers release their latest summer tires–especially the 200-treadwear, extreme-performance summer tires that have become so popular for autocross and track participants.

This year’s class includes only one updated tire, but it comes from Dunlop, long a stalwart of the group. Their Direzza Z1 first came out 10 years ago, and the line has been steadily improving through regular updates every year or two. Dunlop typically releases these new tires in Japan first, with U.S. customers getting them about a year later.

True to form, the Japanese-market ZIII superseded the ZII Star Spec a year ago. Thanks mostly to a revised compound, Dunlop claimed, the new tire shortened lap times by 1.5 percent. Does that hold true for the new USDM version? We decided to find out.

The current top dogs in the category for both autocross and time trial are the BFGoodrich g-Force Rival S 1.5 and the Bridgestone Potenza RE-71R. Since we haven’t done a direct comparison of these two in quite some time, we chose to put both of them in the test loop. Further, in addition to having our usual two drivers, this time we tested tires on two different vehicles–each one set up for a different class and featuring different rim widths. We also added a completely separate venue, a track test, into the mix.

We chose the common 205/50R15 tire size and rounded up the necessary rims. Three sets of 15×8-inch 6UL wheels from 949 Racing came out of our garage, along with a similar quantity of 15×6- and 15×7-inch wheels supplied by friends.

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red_stapler
red_stapler Dork
7/12/18 10:31 a.m.

It looks like some numbers got transposed on the ES car results.

Randy_Forbes
Randy_Forbes New Reader
7/13/18 12:17 p.m.

Nice informative test!  My only comment is to say that I've been running Dunlop Direzzas on my street cars ('99 M Rdstr, '99 M Coupe & '01 M Rdstr) for several years.  One (1) set of gen one and two (2) sets of DZII SS (all are staggered 235/40x17 & 255/40x17 tires on 7.5" & 9.0" stock wheels for both '99s, and the '01 has 8.0" & 9.5" SSR Comps). They have excellent dry and wet traction__wet traction being frequently tested here in SW FL__inspiring confidence under all circumstances.

The one (1) set of first gen tires should probably be swapped out soon, more due to age than wear, so I will stick with Dunlop, only the DZIIIs this time. 

I should look to see if the DZIIIs come in a 195/65 x 15 for my Healey, currently running on some aged out Hankooks!

Good job guys!

goingnowherefast
goingnowherefast New Reader
7/13/18 2:05 p.m.

So basically once again nothing has changed this year. Want to be fast? Get the RE71R or the Rivals. 

CyberEric
CyberEric HalfDork
7/14/18 6:00 p.m.

Thanks for doing this test guys! It sounds like the Dunlop is in the mix depending on car setup, temp and driving style. 

I confess, I'm having a hard time understanding the results of the wider 225 on the ES car... can someone clarify? Were they all 225 on a 6" wheel on the ES car?

 

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