Hoosier R-6 questions

[Viper X]

Anybody have suggestions for best cold / hot tire pressures for the new Hoosier R-6's at the track?

 

[Luke@tirerack]

R6 Roadrace: The first laps for the tire are critical for setting up the durability and competitive life. The first session should consist of no more than 10-15 minutes of running. The early part of the session should be run at an easy pace, with the speed gradually increased until the end of the session. The final lap should be run at the fastest possible speed. The intent is to achieve maximum tire temperature on the last lap. At this point the car should be brought in and the tires allowed to cool at a normal rate.
During the initial run-in process, the inflation pressure should be 3-5 psi higher than you would normally use. The best progression would have the driver taking 4-7 laps to accomplish this break-in. Each lap should be approximately 7-10 seconds per lap faster than the previous lap. The goal is to have the tire temperature as high as possible on the last lap without "shocking" the tire during the warm-up laps. In essence, no wheelspin, late braking, or sliding. The last lap should be at, or very close, to the maximum possible.
After completing the initial heat cycle detailed above, the length of time the tire is allowed to rest out of service is possibly most important. The barest minimum for this process to be beneficial is 24 hours (not "the next day"). Any less than this is a waste of time. The best situation would allow a week before using the tire again. The tires should be removed from the vehicle while they cure, or the vehicle lifted to remove its weight from resting on the tires.
Proper tire management is a difficult process. The payoff is greatly increased competitive tire life.

 

[Viper X]

Hey Luke,

Thanks for the info. I read that on the web site. It sounds great in a perfect world.

I'm looking for someone who has run R6's on a Viper at the track and the recommended cold and hot tire pressures for this tire.

Know anyone?

Thanks,

Dan

 

[Luke@tirerack]

conditions vary too much to have a 'one size fits all' recommendation

ambient temps
track surface
humidity levels
and many others

all play a role in tire/car set up

here is some general info which may help

Tire Pressure Recommendations for Competition
Traditionally, Hoosier tires have often required higher pressures than other brands. This has changed with the A6/R6.

Roadrace/Track Applications
Vehicle Size Recommended Hot Pressure/Cold Pressure
1800-2200 lbs 34-37+ 26-31
2200-2600 lbs 35-38+ 27-32
2600-3000 lbs 37-41+ 27-32
over 3000 lbs 38-43+ 27-33 +
Higher pressures will improve the performance capability but will require a more sensitive feel to take advantage of the increase.
One characteristic of the tires is the tendency to "skate" initially (when inflation pressures are correct). It is important to resist lowering the pressure to attempt to eliminate this feeling. Dropping the pressure too far may improve the "feel" of the tire however it will also lower the performance and increase the wear rate.

 

[Schulmann]

Here is the track man's, hands-on, answer:

These tires require on going pressure adjustment. For instance you set up all 4 tires to 30psi cold in the morning. You do your 1st session then you check the pressure. You will see a lot of variation in the pressure. For instance I had pressures between 51psi and 42psi in the 4 tires when hot. Then you equalize the pressure to 38psi. Then you return to the track, do your business and after the lapping you check the pressure. Sometime you have to add air, sometimes you have to remove air, depending on the temperature of the track. The important thing is to stay as close as possible to a target PSI something like 40psi.

You will see people on tracks checking all the time their tire pressure. I even check brake, tire, engine and header temperatures. I have a log book for this. Now I revealed my secret

 

[Viper X]

I know that there are lots of variables, not new to the game, but tire pressure isn't that critical at my driving level. I'd just like to get a good idea what most guys start these things at cold. So far, not much feedback.

I have had very good luck with Hoosier VRLs starting at 23 rear, 24 front cold. They heat up to about 30 hot which works very well. All of this depends on the track (right hand or left hand) and the day (sunny, hot or cool).

I've run Toyos and Kumhos and they are pretty similar with cold pressures starting about 27 or 28, hot going up to 35 ish.

I guess I'll try 27 cold rear, 28 cold front and adjust from there. 40 hot seems awfully high for slicks, but these are not true race tires like the VRL slicks. Argh !!!!!

Dan

 

[Jeff Monheim]

I would like to get some more info also on the same topic. Average day temps in the low 80s. Ballpark starting pressure to end up at what hot lap temp??? I have run Sport cups and would not go above 36lbs or the tires get "slick" and dont hold the track, I start at 26lbs in the AM and let pressure out as the day gets warmer. Any info on R6 hoosiers would be nice to know???

 

[mjorgensen Woodhouse]

Jeff,

I would not let the growth continue that far. The more the pressures rise beyond the 10-12% rule from cold pressure during a 20-30 min. hot lapping session the more heat is trapped in the tire making it greasy which raises the temps even further each session. Not only is the tread getting greasy but the contact patch is deceasing in small amounts with the increase generating even more heat! Add all these things up and you have a poor handling, tire ruining machine! ESPECIALLY on a Hoosier.

FWIW

I would like to get some more info also on the same topic. Average day temps in the low 80s. Ballpark starting pressure to end up at what hot lap temp??? I have run Sport cups and would not go above 36lbs or the tires get "slick" and dont hold the track, I start at 26lbs in the AM and let pressure out as the day gets warmer. Any info on R6 hoosiers would be nice to know???

 

[rcl4668]

I have no experience with the R6 but for track/HPDE events of 4-6 sessions of 15-20 mins each with about a 15-20 min cool down in between, Mark Jorgensen recommended 33 psi cold all around on my 2008 with Michelin PS2 tires. This resulted in hot temps ranging from 38-41 psi and the car felt great during the lapping sessions.

/Rich