5BW - How long before brand new PS4S tires finally have some bite?

[No Usury]

Granted, I know these AI generated answers are often wrong, so my second reference point is John Heinricy. He was a GM engineer in the Performance Division for 40 years and life long race driver. He presently runs a CT4-V BW in the SCCA Touring 2 class. I've been speaking with him and he's been advising me on the setup of my car. He's told me to use 1/16" toe out in the front and 1/16" toe in for the rear.

You do realize this is a thread about the 5BW, yes? It's right in the title.

 

[Kawman]

I'm not an expert, I'm learning as I'm going through this. And yeah, there's a lot of conflicting info out there.

I watched your videos. In "What is Camber? A Simple Explanation" it says most vehicles use positive camber, but racing/off road applications use negative camber. We're dealing with a performance car and all agree we should be using negative camber, right?

In the "Toe (IN/OUT) in Car Suspension" video - re-watch from 4:00 to 4:15 in the video. This video indicates that for racing/performance applications one uses toe out in the front for quicker turning response.

Seems like the difference between toe in and toe out for a RWD car is the desired outcome. If your driving a regular car and your goal is maximum tire life one would use toe in. If your driving a performance car and want improved steering response one would use toe out.

If my conversion is correct 1/16" should be about .14 degrees (.07 per wheel)

 

[Kawman]

And here's another, using your AI tool, and your exact words:

Acting like everything is black and white, that there is only one answer, and your opinion is the only one that matters, is making you look pretty silly here.

Correct, it's not black and white. It seems to come back to what is your goal, improved tire life or improved handling characteristics? According to your video if the goal is tire life, one would use toe in, but if improved handling is the goal, one would use toe out.

Could you please be more specific regarding your point in your AI generated answer. Having read it, it seems to support the idea that toe out is what is appropriate for our cars.

Perhaps I've made an ass of myself by assuming that improved handling was the goal of a Blackwing owner over tire life. Didn't this thread start over a handling concern?

 

[No Usury]

 

[No Usury]

Let's do a reset – back to the discussion about TIRES, GRIP, and TRACTION.

 

[Kawman]

You do realize this is a thread about the 5BW, yes? It's right in the title.

Yes, of course. I stated the specs I was told to use for my 4BW. I've never said what specs you should be using for your 5BW.

I have only addressed the concept of toe in versus toe out, which doesn't change based on the model or make of a car. I enjoy the learning, so bring more info to the table. So far every reference point we've looked at indicates toe out in a performance application such as a Blackwing.


PS - Just saw your last message. Fine, go enjoy your conversation on how long it takes into the life of a tire before it starts to develop some traction.

 

[nordique14]

Refer to page 3 of the attachment for GM’s track alignment recommendation. They do not recommend toe out. I personally have run toe out and find it very good for autocross as it increase the car’s willingness to turn into a corner. But I find it less desirable on track (and on the highway) as the car feels a lot less stable on the straights at the high speeds this car can achieve. Like most things, there trade offs and you have to decide which attribute is more important.

But back to the OP’s problem of the back end easily stepping out. It is not due to alignment as it is set up to make his car more stable with reduced oversteer.

 

[NorCal Blackwing]

Re: the earlier questions about ambient temps, I'm going to assume the OP is well aware of it but with cold tires, cold ambient temps and slightly greasy roads it absolutely snaps out a bit even on light throttle with the car in Tour, and it starts right round this time of year... just a PSA for others perusing these threads. When fall and winter roll around my instagram fills up with pics of GT3's upside down in ditches, folks who decide to go for a morning rip on their Cup2s.

 

[CB34]

Just swapped on Alpin PA4's onto my 5BW. Absolute night and day in traction and off the line acceleration. It's not even that cold - car is kept in a garage with roughly 60 degree ambient temp's and outside temps have varied 52-65 over the past few weeks or so.

The recommendation is to not drive with these tires under 50. This has been a generic line from GM for any car that came with summer high performance tires. I think these TPC Spec PS4's really only hook up when you have ambient temps at 72-75+ as that's when they felt the best to me.

 

[hawk02]

Just swapped on Alpin PA4's onto my 5BW. Absolute night and day in traction and off the line acceleration. It's not even that cold - car is kept in a garage with roughly 60 degree ambient temp's and outside temps have varied 52-65 over the past few weeks or so.

The recommendation is to not drive with these tires under 50. This has been a generic line from GM for any car that came with summer high performance tires. I think these TPC Spec PS4's really only hook up when you have ambient temps at 72-75+ as that's when they felt the best to me.

I’ve never seen GM say you can’t drive PS4S under 50°. Under 20°, yeah — that’s when you really need to be careful. If 50° were the limit, no one up north could drive their Blackwing in spring or fall. Sure, they lose grip when it’s cooler, but they’re not gonna crumble or crack just because it’s chilly. I’ve driven on PS4S in 25° weather — you just can’t do dumb stuff. No cracks, no issues, just less traction till they warm up.

 

[Kevin0311]

25+ has tire temp when have the tire pressure menu on the screen, cold, normal, hot

 

[Stephen Navarra]

Brand-new 5BW, less than 1K miles.

Was on the freeway cruising at 65 when I decided "Meh. Let's try 75."

Lightly touched the gas... and she got squirrelly... to and fro, left and right.

No brown, but pucker factor was > 0. I mean I lightly touched the gas.

Is this the tires, the car, combination, or something else?

Brand-new 5BW, less than 1K miles.

Was on the freeway cruising at 65 when I decided "Meh. Let's try 75."

Lightly touched the gas... and she got squirrelly... to and fro, left and right.

No brown, but pucker factor was > 0. I mean I lightly touched the gas.

Is this the tires, the car, combination, or something else?

Never this is the only problem with blackwings the break loose buy the all weather tires it helps a bit

 

[No Usury]

Never this is the only problem with blackwings the break loose buy the all weather tires it helps a bit

They're on the way...

 

[CornerMan]

To revisit this for anyone who may find it useful down the road (no pun intended). I had also been struggling with that wandering, “squirrely” feeling under acceleration. A few factors that may have been overlooked in earlier discussions:

1. Tire pressure matters. Higher pressure resulted in noticeably less traction. I felt a significant difference going from 35 PSI cold to 29 PSI cold in the rear - a very easy adjustment to start.
2. Lowering changes geometry. Even a modest drop (0.7") alters suspension geometry. The car seems to toe out under acceleration due to rear squat regardless, but the effect is amplified once lowered.
3. Rear toe arm flex. I’ve read on other forums that the stock rear aluminum toe arms can flex under acceleration, which can also contribute to toe-out behavior.
4. Toe-in improves stability and ensures you never toe-out under acceleration squat. Aligning with approximately 0.2 degrees of toe-in provides added stability for street driving.

I’m happy to say I’ve finally found the formula that works for my car after three alignments and a fair amount of frustration:

1. SPL rear toe arms – These address potential flex and reduce the risk of bolts loosening over time.
2. Alignment: -1.5 degrees camber all around, with 0.18 degrees of toe-in front and rear (I asked for 0.20, just ended up at 0.18).
3. Tire pressure: 29–30 PSI cold in the rear (approximately 31–32 PSI in the front).

Note: My car is lowered on Eibach springs.

This may not be the perfect setup for everyone dealing with this issue, but it solved it for me. The car now hooks the way it should given the power, and I’ve regained confidence in daily street driving.

PS: I do not track the car. This is strictly a street setup.

Hope this helps anyone else dealing with this issue!

-eric

 

[No Usury]

To revisit this for anyone who may find it useful down the road (no pun intended). I had also been struggling with that wandering, “squirrely” feeling under acceleration. A few factors that may have been overlooked in earlier discussions:

1. Tire pressure matters. Higher pressure resulted in noticeably less traction. I felt a significant difference going from 35 PSI cold to 29 PSI cold in the rear - a very easy adjustment to start.
2. Lowering changes geometry. Even a modest drop (0.7") alters suspension geometry. The car seems to toe out under acceleration due to rear squat regardless, but the effect is amplified once lowered.
3. Rear toe arm flex. I’ve read on other forums that the stock rear aluminum toe arms can flex under acceleration, which can also contribute to toe-out behavior.
4. Toe-in improves stability and ensures you never toe-out under acceleration squat. Aligning with approximately 0.2 degrees of toe-in provides added stability for street driving.

I’m happy to say I’ve finally found the formula that works for my car after three alignments and a fair amount of frustration:

1. SPL rear toe arms – These address potential flex and reduce the risk of bolts loosening over time.
2. Alignment: -1.5 degrees camber all around, with 0.18 degrees of toe-in front and rear (I asked for 0.20, just ended up at 0.18).
3. Tire pressure: 29–30 PSI cold in the rear (approximately 31–32 PSI in the front).

Note: My car is lowered on Eibach springs.

This may not be the perfect setup for everyone dealing with this issue, but it solved it for me. The car now hooks the way it should given the power, and I’ve regained confidence in daily street driving.

PS: I do not track the car. This is strictly a street setup.

Hope this helps anyone else dealing with this issue!

-eric

How do your tires wear with -1.5 front and rear?