A tale of two tires (brands)

[Greengohellcat]

Matt, you need to put away the 1.1 second thing.

Guys I have beat the snot out of 285/35's on 9.5" rims (PS4S) on our track, they are NOT unstable. All of last season videos with my '15 are on those.

What kind of speeds do you get er up to on the track?

 

[Magnified]

I'm not saying all of these tires, or all applications, are unstable, only that it is what I personally experienced in the specific circumstances of my usage and I'm not sure the word unstable is accurate or the most descriptive. These events did not happen in cornering but on straights under hard acceleration (there were changes in grade in most of these situations, but not dramatically). They consisted of the rear of the car oscillating from side to in the rear under WOT, not in an out of control manner, but it would slowly oscillate from side to side completing 3 oscillation in about 4 seconds. I did not notice the traction system interfering at all, but it is possible as it was in track and that remains active in some way though I have never been able to get details, even from SRT, on exactly how the system is programmed to act in track mode. Suspension was in street mode. This oscillating behavior was almost always experienced with relatively fresh pavement (out here, that's mostly black, and eventually weathers to grey or white depending on composition).

The only cornering related weirdness with the tire was in a long sweeping left hand turn that had serious waves and undulations in its surface and the speed was 100-120, mostly at WOT. I would best describe it as a wobble. I did not have the sensation I got with the PS4S in that location and that situation with other tires, even drag radials. I've noticed that the Charger (at least) is particularly sensitive to crossing lengthwise road humps (what I like to call "wake lines" often the results of heavy over loaded truck traffic that squeeze the humps up on either side of the wheel tracks). I don't mean you'll instantly lie in flaming carnage when you cross them, but that the car reacts with a wobble as it crosses from one side to the other and, at least in my experience, the degree of wobble increases with speed. This sensitivity is more pronounced, and in my experience, than in other high performance cars. Now, it should be recalled that I did all this in "street" suspension setting (if I remember correctly) and that and the track traction setting could play a role, I'm not sure.

I don't think any one involved in the discussion is saying that other persons are lying about what happened, or incompetent, poor observers, or whatever. I personally think people are just experiencing different things with some of these tires. Whether those things are artifacts of some manufacturing defects, specific road surfaces, specific climate, or the interaction of the various electronic systems in the car working at varying settings, or a combination of all or some of those, something odd is happening at times. I know I spent ages deciding and researching tires before I picked up that set of PS4S a year or more back, and fully expected them to be exceptional, but I was surprised by how they acted in those specific settings described above. Why that happened, I cannot (and am not attempting to) say, but I am reporting what I experienced. People can make what they wish of all the reports and experiences everyone is contributing. It's easy to come across in an unintended manner and I think we all should remember that none of our fellows on here are criticising or calling into question what people are saying.

That's my two cents, for whatever that's worth.

 

[Greengohellcat]

I'm not saying all of these tires, or all applications, are unstable, only that it is what I personally experienced in the specific circumstances of my usage and I'm not sure the word unstable is accurate or the most descriptive. These events did not happen in cornering but on straights under hard acceleration (there were changes in grade in most of these situations, but not dramatically). They consisted of the rear of the car oscillating from side to in the rear under WOT, not in an out of control manner, but it would slowly oscillate from side to side completing 3 oscillation in about 4 seconds. I did not notice the traction system interfering at all, but it is possible as it was in track and that remains active in some way though I have never been able to get details, even from SRT, on exactly how the system is programmed to act in track mode. Suspension was in street mode. This oscillating behavior was almost always experienced with relatively fresh pavement (out here, that's mostly black, and eventually weathers to grey or white depending on composition).

The only cornering related weirdness with the tire was in a long sweeping left hand turn that had serious waves and undulations in its surface and the speed was 100-120, mostly at WOT. I would best describe it as a wobble. I did not have the sensation I got with the PS4S in that location and that situation with other tires, even drag radials. I've noticed that the Charger (at least) is particularly sensitive to crossing lengthwise road humps (what I like to call "wake lines" often the results of heavy over loaded truck traffic that squeeze the humps up on either side of the wheel tracks). I don't mean you'll instantly lie in flaming carnage when you cross them, but that the car reacts with a wobble as it crosses from one side to the other and, at least in my experience, the degree of wobble increases with speed. This sensitivity is more pronounced, and in my experience, than in other high performance cars. Now, it should be recalled that I did all this in "street" suspension setting (if I remember correctly) and that and the track traction setting could play a role, I'm not sure.

I don't think any one involved in the discussion is saying that other persons are lying about what happened, or incompetent, poor observers, or whatever. I personally think people are just experiencing different things with some of these tires. Whether those things are artifacts of some manufacturing defects, specific road surfaces, specific climate, or the interaction of the various electronic systems in the car working at varying settings, or a combination of all or some of those, something odd is happening at times. I know I spent ages deciding and researching tires before I picked up that set of PS4S a year or more back, and fully expected them to be exceptional, but I was surprised by how they acted in those specific settings described above. Why that happened, I cannot (and am not attempting to) say, but I am reporting what I experienced. People can make what they wish of all the reports and experiences everyone is contributing. It's easy to come across in an unintended manner and I think we all should remember that none of our fellows on here are criticising or calling into question what people are saying.

That's my two cents, for whatever that's worth.

What tires are on the Hellcat now?

 

[Magnified]

Right now, I'm running 305 555Rs on the rear (on 11 x 20 look alikes by Paul and PKA). On the front, stock rims and OEM all-seasons. For serious highway work, where rain can be expected, I have the OEM all-seasons on the stock rears that I swap on.

 

[Greengohellcat]

Magnified, since you tried the PS4S (top rated road tire) did you consider the Conti ECS at all?

 

[ACMAVRO]

Now Im second guessing getting the PS4's

 

[HRJ]

I was going to fit PS4's when I changed my Pireilli summer tyres last year. I spoke with a company that supplies a lot of race tyres. He said do not fit PS4's as the side wall is too soft and recommended pilot sports. I fitted the pilot sports and they too have a soft side wall and the back end of the car on the strip would be like a tank slapper on a motorbike when aired down and they were real squirrely on the road. It felt like the bushes in the rear trailing arms were shot..

VERY good description of what I experienced with the Michelin. Also somewhat solidifies my guess as to the sidewall stiffness (or lack of) being the culprit.

 

[HRJ]

I'm not saying all of these tires, or all applications, are unstable, only that it is what I personally experienced in the specific circumstances of my usage and I'm not sure the word unstable is accurate or the most descriptive. These events did not happen in cornering but on straights under hard acceleration (there were changes in grade in most of these situations, but not dramatically). They consisted of the rear of the car oscillating from side to in the rear under WOT, not in an out of control manner, but it would slowly oscillate from side to side completing 3 oscillation in about 4 seconds. I did not notice the traction system interfering at all. Suspension was in street mode.

That reflects my experience. I experience a more violent oscillation that you seem to have, and at a higher frequency, but very similar.

I'm definitely not trying to throw shade on anyone's tire choices, just wanted to share my experience. When I first experienced this I did my research and found some posts out there on the ol' interwebz talking about this issue along with some debate back and forth, but nothing conclusive. I will say that my situation is pretty conclusive for how I use my car.....long stretches of flat, straight road accelerating hard.

 

[Hellcatcfp]

Much appreciated info on here. PS4s seem to be best for everyday boring driving duties which I do a lot. Guess if I decide to track it I need a whole other setup. Summer P-Zeros aren't perfect, but can tolerate them except for that vibration at 77-80 which I drive a lot at. Kinda of stumped at which way to go now...no sure on PS4s. Great info.

 

[DGatzby]

What kind of speeds do you get er up to on the track?

165

 

[Greengohellcat]

165

Wow, and the tires are obviously not misbehaving.
Interesting.

 

[HRJ]

Wow, and the tires are obviously not misbehaving.
Interesting.

Well, his tires aren't the factory sizing either. Maybe there's something on how a 285 sits on the 9.5s compared to the 275s. Or maybe it's a pressure difference. I run all mine at factory pressures (32 cold), not sure what DGatzby runs on the track. Also, his are PS4S tires. I had PS4 tires. Not sure on what construction differences there are between the two.

Never even thought about bumping pressure on the Michelins, but I didn't want that 3/4 ton truck ride, either.