Extreme performance tires in SCCA newsletter

[jwmelvin]

Since the Solo (autocross) rules now require at least 200 treadwear tires for the "street" and "street touring" categories, SCCA published a test they did of four such tires, using identical cars (FR-S race cars) on an autocross course. They first did a bunch of runs to optimize tire pressure for each. Since some of them are available in NSX sizes, I thought you might be interested.

Tire	Lateral G	Best dry lap	Best wet lap	psi
Hankook Ventus R-S3 v2	1.1	29.290	29.9	32
BF Goodrich G-Force Rival	1.0	29.583	29.7	35
Bridgestone RE-11	0.98	29.568	29.2	32
Dunlop Direzza ZII Star Spec	0.90	29.723	29.2	30

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[nsxtasy]

Tire Rack recently did a similar test of four such tires (including three of those above, not the RE-11, but with the Yoko AD08R). Their test included a lot more data (including testing them at different temperatures). Click here.

 

[jwmelvin]

Thanks for the link.

Funny that their ranking was nearly opposite the SCCA test.

 

[Hapa88]

Thanks for the link.

Funny that their ranking was nearly opposite the SCCA test.

TireRack's times are much more believable too with there being up to 2 seconds between tires. The SCCA ones are all within less than 5/10s of a second... that's just noise right there on a 30 second run.

Also, it looks like out of the lists, only the AD-08R, the BF Goodrich and the Dunlops are available in NSX sizings commonly used. I only searched matching pairs of 215/45/16 with 255/40/17, 215/40/17 with 255 or 265/35/18, and 215/40/17 with 255/40/17.

 

[jwmelvin]

I would have thought that 0.5 sec over a 30 sec autocross course is very significant and repeatable for an experienced autocrosser.

The Hankooks require a 205 front tire in 16" diameter; not available in 17".

 

[Midnight_Raven]

That table doesn't seem right. 2 of the 4 tires run faster times wet than dry.... how is that even possible lol.

 

[BlackTop99]

That table doesn't seem right. 2 of the 4 tires run faster times wet than dry.... how is that even possible lol.

Especially suspect since the best time is a wet lap on the tire pulling the lowest lateral G's? Can you post a link to the article in question? scan it? or check that grid you posted? thanks!

 

[jwmelvin]

Especially suspect since the best time is a wet lap on the tire pulling the lowest lateral G's? Can you post a link to the article in question? scan it? or check that grid you posted? thanks!

Yes, I must have botched something; I will be able to look at it on Tuesday and will correct it then. Sorry.

- - - Updated - - -

Hm. I dunno. It looks like you can see it online:http://www.sportscarmag-digital.com/sportscar/february_2015#pg30. And I believe I typed the numbers in correctly. They refer to an "abbreviated" wet course, so it seems that the wet and dry courses were not the same. They also noted that they ran the same 40 psi for all the tires in the rain, not the optimized pressure (because the 40 psi was typically what those cars run on the streets of Long Beach). It's worth reading the article for the comments/discussion of each tire. I don't want to copy/post the entire thing here.

The table:

 

[scammy]

I have the Dunlop's on my car and there is no way they are faster in the wet on a track, I have tracked it numerous times in the dry and wet on the same day at the same track

 

[jwmelvin]

The scca test for wet and dry was not the same track. Nobody is saying a tire is faster in the wet than the dry.

 

[Hapa88]

I would have thought that 0.5 sec over a 30 sec autocross course is very significant and repeatable for an experienced autocrosser.

The Hankooks require a 205 front tire in 16" diameter; not available in 17".

Sorry, I meant to say that the max spread is that much. The variance between most is even smaller than that. Its also weird to me that all the Dry laps are posted down to the thousandths of a second, where the Wet Laps are only to the tenth.