ACR tire pressures?

[Grant]

The Viper Magazine ACR setup article suggests that we should look for hot tire pressures in the 35-36 range on the ACR. I'm wondering a few things:

A) Is this the optimal front and rear tire pressure to use when the ACR is set up to SRT's recommendations?

B) Is the optimal tire pressure going to vary with the speed of the turn? This is my first time driving a downforce car, but I know a heavier car will, all other things being equal, require more tire pressure. I would think the same would be true of downforce: More tire pressure is needed for higher speed corners? 35-36 psi is considerably higher than what most people run for hot pressures on pilot sport cups in other cars.

I have a probe-type pyrometer, but haven't been able to get off the track with the tires hot. I'm seeing average (not peak!) lateral gees of 1.20 to 1.25 on steady-state ~55 mph corners, which I think is pretty good.

 

[SoCal Rebell]

The Viper Magazine ACR setup article suggests that we should look for hot tire pressures in the 35-36 range on the ACR. I'm wondering a few things:

A) Is this the optimal front and rear tire pressure to use when the ACR is set up to SRT's recommendations?

B) Is the optimal tire pressure going to vary with the speed of the turn? This is my first time driving a downforce car, but I know a heavier car will, all other things being equal, require more tire pressure. I would think the same would be true of downforce: More tire pressure is needed for higher speed corners? 35-36 psi is considerably higher than what most people run for hot pressures on pilot sport cups in other cars.

I have a probe-type pyrometer, but haven't been able to get off the track with the tires hot. I'm seeing average (not peak!) lateral gees of 1.20 to 1.25 on steady-state ~55 mph corners, which I think is pretty good.

At Willow Springs, the "Fastest Track in the West" 36-36 psi is dead on, with a track alignment. I start at between 28-30 psi, taking a 90 degree left at 90+ mph and a long sweeper at 130-140 mph. The Cups are a great tire, they have a short life but work great at high speeds. They hold the track right down to the cords, I used to run my R3SO6's at 40 psi hot on my Gen 2, 36 psi hot is perfect in the ACR on Pilot Cups.

 

[rcl4668]

At Willow Springs, the "Fastest Track in the West" 36-36 psi is dead on, with a track alignment. I start at between 28-30 psi, taking a 90 degree left at 90+ mph and a long sweeper at 130-140 mph. The Cups are a great tire, they have a short life but work great at high speeds. They hold the track right down to the cords, I used to run my R3SO6's at 40 psi hot on my Gen 2, 36 psi hot is perfect in the ACR on Pilot Cups.

SoCal -- Are your 28-30 psi start pressures true cold pressures that you set in your garage the morning of the track day or are they the pressures you start with after having driven to the track? I am thinking about getting a set of the Sport Cups and am very interested in real world pressure data. This would just be for driving schools/track days with 4-6 sessions approximately 20-30 minutes per session. Thanks.

/Rich

 

[SoCal Rebell]

SoCal -- Are your 28-30 psi start pressures true cold pressures that you set in your garage the morning of the track day or are they the pressures you start with after having driven to the track? I am thinking about getting a set of the Sport Cups and am very interested in real world pressure data. This would just be for driving schools/track days with 4-6 sessions approximately 20-30 minutes per session. Thanks.

/Rich

They are "at track" pressures. At WSIR because it is a clockwise track I go 28 psi front drivers, 29 psi front passanger, 29 psi rear drivers & 30 psi rear passanger. On a warm day that gets me up to 36 psi hot on all corners. That's with the rear wing at the #2 stock setting and the track splitter on. The Cups are a great tire, but will get expensive over time.

 

[rcl4668]

They are "at track" pressures. At WSIR because it is a clockwise track I go 28 psi front drivers, 29 psi front passanger, 29 psi rear drivers & 30 psi rear passanger. On a warm day that gets me up to 36 psi hot on all corners. That's with the rear wing at the #2 stock setting and the track splitter on. The Cups are a great tire, but will get expensive over time.

Thanks SoCal.

/Rich