More tire advice needed...


TEXAS GT

2006 Twin Turbo
Mark IV Lifetime
Le Mans 2010 Supporter
I'll tell you what I'm considering and then all of you can shoot holes in it.

I need tires that will max out my traction in a straight line. I'm not going to track the car and probably will not ever put it on a drag strip. My venue for these tires will be straight line, high speed events like the Texas Mile where I will need enough traction to handle 850+ horsepower off the line, and high speed (200 mph +) dependability.

I won't get much of a chance to warm the tires up and tread life is not an issue. I won't be driving on the street with these tires installed so being DOT legal and wet weather traction aren't important.

So far my frontrunner is the Hoosier A6 autocross tire. It's a softer compound than the R6 so it will grab better with less warmup. It's the tire that Peak ran on his car when he did several 210+ mph runs in the Car and Driver shootout as well as the Texas Mile so we know it will hold together. All the other drawbacks related to Hoosiers that I've read on the forum won't apply because of the above reasons.

I also see no reason (please correct me) to change the front tires. The stock Goodyears are apparently trustworthy at the speeds being discussed and extra traction is not needed to keep the car in a straight line. There may be some advantage to using Hoosiers on the front for increased braking traction at the end of the run but I doubt it would be enough to justify the expense and trouble. There's also the issue of sandblasting the side of the car. Hoosiers on the front would probably do more damage than the stock tires.

I'm sure there are a variety of race slicks out there that you might suggest but I believe they would require the use of different size wheels that wouldn't match the front ones and high speed dependability would worry me. The small amount of traction advantage, if any, wouldn't justify the oddball look of mismatched wheels. We do have an image to uphold after all.:biggrin

Let the games begin. Any and all suggestions and opinions are appreciated.
 

BlackICE

GT Owner
Nov 2, 2005
1,416
SF Bay Area in California
You got it right! A6 should fit your needs. However you may also consider using A6s in the front too, if braking distances are at all important as well. Weight transfers the front during braking and front tire traction is important.

:thumbsup
 

dbtgt

One lucky SOB to own a GT
Mark IV Lifetime
Jan 4, 2006
1,106
Tulsa, Oklahoma
You got it right! A6 should fit your needs. However you may also consider using A6s in the front too, if braking distances are at all important as well. Weight transfers the front during braking and front tire traction is important.

:thumbsup

+1 :agree:
 

kumar

GT Owner
Jan 31, 2007
1,011
Dallas
I was also going to suggest using the same tires in the front. The tread pattern in the front and pretty much no tread in the back might cause issues with how the car tracks, especially at those speeds.


BTW, what do you have up your sleeve? Race gas tune for the whipple or turbos?
 

Howard

GT Owner
Mark IV Lifetime
Apr 26, 2007
1,149
Florida/North Jersey
What does Hoosier have to say about 200+ mph on A6's? Despite the experiences of others, Hoosier could not have taken such speeds into consideration when deveolping an ultimate autocross tire.

Howard
 

TEXAS GT

2006 Twin Turbo
Mark IV Lifetime
Le Mans 2010 Supporter
Upon further investigation, it seems that Hoosier doesn't offer the A6 in the stock size of 315/40-19. You have to step up to 325/30-19 but that size is much smaller in diameter and circumference than the 40 series. That means it would be spinning much faster at any given speed which might not be good at 200+.

I tried to contact Hoosier for top speed info (which is what their website advises) but everybody was gone racing.

The established fact remains that the A6 has proven itself at 225 mph several times on Rays car even though he must have been running the 30 series. Maybe Ray would chime in here with his experience??? Ray??? You out there???
 

BlackICE

GT Owner
Nov 2, 2005
1,416
SF Bay Area in California
Upon further investigation, it seems that Hoosier doesn't offer the A6 in the stock size of 315/40-19.

I believe they made them at one time. Torrie bought the last 4 of the 5 that were on closeout sale at Tirerack for only $90 each!
 
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TEXAS GT

2006 Twin Turbo
Mark IV Lifetime
Le Mans 2010 Supporter
I believe they made them at one time. Torrie bought the last 4 of the 5 that were on closeout sale at Tirerack for only $90 each!

I finally talked to a Hoosier rep today. Their official stance on their DOT legal tires is that they ARE street legal. They go through all the same testing that any other street legal tire does. There are several race sanctioning bodies who require DOT legal tires in certain classes. All the legal disclaimers on their website are directed more at their offroad race tires but also to give them some protection in case some fool wants to sue them after he crashes his Porsche racing on the street.

And, yes, they figured out that not a lot of GT drivers are autocrossing their cars so they have dropped the A6 in our size for the rear. They still have a few left in their closeout section at a killer price of $165 and free freight if anybody wants some. I bought two because he said the A6 would be better for traction off the line with little or no warmup.

He also said while they don't list top speeds for their tires, they have been tested on roller drums well beyond 200 mph and said I would have no tire issues at short bursts up to those speeds. He definitely didn't recommend extended driving at 200 plus but then what tire company would?

So if you have a wreck on the street with Hoosier A6s or R6s, your insurance company may question your judgement, but they can't deny your claim.
 

BlackICE

GT Owner
Nov 2, 2005
1,416
SF Bay Area in California
Thanks for the info. Now can we get that in writing? I didn't think so. The Hoosier attorneys are not that dumb.
 

MAD IN NC

Proud Owner/ BOD blah bla
Mark IV Lifetime
Feb 14, 2006
4,219
North Carolina
They still have a few left in their closeout section at a killer price of $165 and free freight if anybody wants some. I bought two because he said the A6 would be better for traction off the line with little or no warmup.

Just picked up 2. Best price outside of Hoosier was TireRack for $379 - Thanks Texas GT!



Now for the fronts - looking at the Dunlop Sport 9000...
Size would be 255/45ZR/18 Piko 6 swears by them.

Thoughts?
 
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tmcphail

GT Owner/Vendor
Mark IV Lifetime
Apr 24, 2006
4,103
St Augustine, Florida
Good thing I picked up 4 from tire rack for $90 a piece woohoo !
 

roketman

GT Owner
Mark IV Lifetime
Oct 24, 2005
8,086
ma.
The Hoosiers are awesome !!!!!!
Braking ,cornering and acceleration much improved .
They last just as long as the Goodyear F1
 

John B

GT Owner
Mark II Lifetime
Jan 28, 2006
158
Be careful here!!
The A6 is designed for autocross where max speeds are probably 60 - 80 mph and likely can not handle the forces of sustained 210 mph+. I strongly recomend you speak with someone at Hoosier about your intended use.
Call Bruce Foss at Hoosier, 574 784 3152.

Think about it. Centrifigal force is forcing the tire mass away from the center of the wheel, then once per rotation the tire bears 1/4 of the weight of the car, say 900 lbs for arguments sake. The faster the tire rotates the stronger the centrifigal force is and also the faster the frequency of the on/off weight bearing. It is easy to see how a tire not designed for sustained 210+ would self destruct in short order. Higher pressures will help reduce the on/off weight bearing stress. If Hoosier says the A6 is OK for this, ask them what pressure you should run for your high speed passes.
 

TEXAS GT

2006 Twin Turbo
Mark IV Lifetime
Le Mans 2010 Supporter
Be careful here!!
The A6 is designed for autocross where max speeds are probably 60 - 80 mph and likely can not handle the forces of sustained 210 mph+. I strongly recomend you speak with someone at Hoosier about your intended use.
Call Bruce Foss at Hoosier, 574 784 3152.

Think about it. Centrifigal force is forcing the tire mass away from the center of the wheel, then once per rotation the tire bears 1/4 of the weight of the car, say 900 lbs for arguments sake. The faster the tire rotates the stronger the centrifigal force is and also the faster the frequency of the on/off weight bearing. It is easy to see how a tire not designed for sustained 210+ would self destruct in short order. Higher pressures will help reduce the on/off weight bearing stress. If Hoosier says the A6 is OK for this, ask them what pressure you should run for your high speed passes.

I did talk to a Hoosier rep, I forget his name but he was very knowledgable and confident about the info he gave me. He actually recommended the A6 for my use at the Texas Mile and 200 plus mph. He said the only difference in the A6 and R6 was the compound.

We also have the fact that PeakCompletions used the A6 on his 222 mph run last year at the Mile with no tire issues.

I will be doing some research on pressure, though.
 

S592R

GT Owner
Mark IV Lifetime
Dec 3, 2006
2,800
Here is the link to the care and break in for the A6/R6 .

http://www.hoosiertire.com/Tctips.htm

Link has air pressure setting warm and cold.
 

Derry

GT Owner
Mark II Lifetime
Apr 5, 2006
345
buffalo, NY
On the Hoosier page for discontinued tires they are $165 each??
 

DoctorV8

GT Owner
Mark IV Lifetime
Feb 28, 2006
1,173
Houston
On the Hoosier page for discontinued tires they are $165 each??

Yup....just ordered a pair!
 

HeritageBruce

GT Owner
Mark II Lifetime
Mar 13, 2006
748
Southern CA
I ordered a pair also, thanks for the tip. Hope the fronts go on sale soon. Wonder if the R8 or R9's are going to be out soon?