cgh1

That is an AWESOME picture!!
I've been needing a new pic for my classrooms showing sidewall deflection. The one I've been using is tired and taken from too far away. (And uses a BMW... ) Do you mind if I use this one?

Fantastic!!

Thanks for posting!

XPC5R

Don't try without adult supervision - 335's at around 17psi Slick asphalt sucks

WBHighwind

That picture is amazing.

Oh, and XPC5R, your car gives me funny feelings in the gentleman region every time I see a picture of it.

drivinhard

go for it

mikahb

Doesn't look too bad to me - I guess I've seen it enoough times that I expect that kind of movement anymore. Trying to use air pressure to make this go away will slow you down, probably a bunch.

I ran Kumho's, but I'd start them at 19-20R and 20-21F to get excellent grip and wear when hot (~28psi). They're a little squishy for a lap or so, and they will spin on the wheel, but they grip well and wear nicely.

SIK02SS

Hoosier A6's and I start them cold around 19/18 and that varies on track conditions, temps, etc..I usually finish the session with them right up at 30 all around and last time out took tire temps as well, had less than a 10* temp difference all around

but I'm slow..and I haven't marked a tire to see how much I spin it

BrianCunningham

ryan0

http://www.youtube.com/watch?v=cfddsOd3jgE

BrianCunningham

I remember a similar video during an ALMS race.

You could see the coilover rotating.

The engineers were glad to see it since it wasn't suppose to do that!

It was fixed the next race, and they thanked the network for finding it!

ryan0

i was searching for a NASCAR one the broadcast.. now THAT was sidewall deflection.

Z06cool

No big deal Mark, you could have just grabbed the tire back up going down the essses -- like this guy.

http://www.youtube.com/watch?v=N_9ycZq6iJ4

VetteRacer725

Awesome picture!!!

John Shiels

I still don't think the lower pressure is faster, I do think it would feel much easier to drive.. I start at 32-33 front and 31 rear end up at about 42 hot depending on temps of the day on all 4. I'd be running on the side walls. I do have 2.5 or a tad more I forgot and 1.5 rear. I am not doing W2W but I bury a bunch of cars even with be HP they have and the tighter it gets the farther most are behind. When I get back on track I have to see the low pressures work.

ryan0

you must know something that hoosier and every single winning racer doesnt.

John Shiels

I would not even have any car control. tires would be gone in 2-3 sessions. I tried them low once and it was horrible./


here it is right from Hoosier




TIRE CARE TIPS
FOR R6 & A6 TIRES
(Download Printable Version)

The R6 and A6 have been developed to improve wear and consistency without any sacrifice of performance. In many cases, the performance will even improve over previous models. The new tire models are an evolution in the continuing effort to provide the best tire for racers.

- Tire Break-In Procedure
- Tire Temperature Recommendations
- Chassis Setup Recommendations
- Tire Pressure Recommendations
- Things to Consider

Tire Break-In Procedure
Proper break-in will not affect initial performance but will increase the competitive life of the tire.

The procedure can be broken down into phases.

1st phase: The initial run
2nd phase: The length of the time the tire is allowed to "cure"

The Initial Run Heat Cycle

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 temp 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 a lap faster than the previous lap. The goal is to have the tire temp 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, the maximum possible.



A6 Autocross

For autocrossing, the A6 does not need the same break in procedure as the R6. The A6 needs a minimal scuff-in session before the first autocross run. This “session” can comprise of simply driving around the event site at minimal speeds on the A6 set of tires. By scrubbing off the newness of the tread (no or minimal shininess remaining) prior to your first competitive run, the A6 tires will be more consistent in handling, grip and responsiveness on the first run. If this is not completed, running on un-scuffed A6 tires on your first run may result in the tires not gripping properly, or feeling like they “skate” over the course surface. You are welcome to run 3 – 5 psi higher when scuffing in a new set of A6’s, but be sure to reset them to the correct operating pressures before your first autocross run. As you compile autocross runs on your new A6’s, they should become more consistent in run times.

"Cure" Time
After completing the initial run phase, the length of time the tire is allowed to set is possibly more 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.

Proper tire management is a difficult process. To accomplish this almost always requires a second set of wheels. The payoff is greatly increased competitive tire life.

Following the recommended break-in procedure will require a lot of planning to make it work. The benefits to doing it right include greatly increased tire life as well as consistent performance and durability under stress. Please make an effort to educate your team on the importance of this. It can save you a lot of money.

Tire Temperature Recommendations

For best performance the expected temperature range will vary from track to track. Generally, optimum traction will be generated when the pit lane temps show 180-200 degrees for the R6 in Roadrace applications, and 140-150 degrees for the A6 in an Autocross application.

Note: Use of static infra-red pyrometers is an inaccurate method to monitor tire temps.

Chassis Setup Recommendations
For optimum performance the Hoosier P-Metric radial tires require about 3 degrees of camber. There will be a trade off in maximum performance to maximize wear. Generally, 1/2 degrees less than optimum will result in the best compromise for wear and speed. Less than 2.5 degrees can result in excessive wear on the shoulder junction.

The Hoosier tires typically offer better performance with spring/shock rates higher than previous brands you may have run.

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.



Autocross applications

For autocross applications, your starting pressure for the first run should be within 1-2 psi of the recommended hot pressures shown above. After the first run and each subsequent run, keep resetting the pressures back to your target hot pressures before taking the next run. This way your tires are at the proper pressure during the bulk of every run you take.

The above chart is a general recommendation which is intended for a standard configuration vehicle (i.e. front engine, rear wheel drive). Factors which can radically affect your pressure set up would include front wheel drive, independent rear suspension, rear engine, McPherson vs. control arm front suspension.

BrianCunningham

ryan0

A6s arent meant to last forever..

and that is hoosiers legal statement on tire pressures.

low pressures may not be recommended for everyone... but to get them to go the fastest for one race?.. youre starting under 20psi.

John Shiels

I run R's so is that what we are talking about on a track event or race not a 30 second autoX? Legal statement? That will save them from what? When you start at 20 they end up where hot? They will be flexing a ton so that will create a ton of heat. I try to be back on track this year at the end I want to see a 20 lb car in front of me and watch it handle.

drivinhard

I've talked to Hoosier techs through the NASA contingency program several times this year, and I pressed them on the pressure issue.

Basically, there's an recommended pressure, and there's an "off the record" recommended pressure

drivinhard

Sorry Khoi, luck does not follow me around like that.

That would happen to Jason though