ibleedblue82

Hello everyone!

I feel like I've lurked here for the greater part of my adult life (I'm 40) and I've recently been able to purchase my first Porsche, a 2020 C2 thats CPO with 14K miles. Coming from other cars such as C6/C7 ZO6's, multiple GTR's and GT350/GT500's, I feel like I have a reasonable expectation of what the base 992's braking should be and what it won't be. However, I've been disappointed so far in terms of hard braking at higher speeds, For example, I may get an opening on the highway and I mash it a bit, reach 115 then get on the brakes hard to get back under the limit. In these scenarios, the car seems to dart around and wiggle. I'm not sure if its the front tires trying to bite or the back end wanting to come around. Its not as if the car is out of control but the braking is certainly not linear as I am used to. Its still not a comfortable feeling and I find it hard to believe that this is "normal."

The car has stock everything, with 19/20 wheels with OEM Pirelli's.

Thanks,
Josh

Richard_Wallace

Also in Cincinnati with a few 911's including 992's. You should not feel any wiggle at all, and honestly of all the cars you list, you should feel more secure in your breaking than you do with most/if not all those listed (though the GTR and Z06 should be pretty decent as well.

Let me ask you - when did you get the car. Meaning if you are trying the 115 to slow down in under 40-50 degree weather recently, it is 100% the summer tires. They will perform terrible in anything below 50 degrees (and 40 and below, actually dangerously like they will not have grip.)

Knowing our temps the last month here in Cincy, I am thinking it is either your tires (as it has been pretty cold) this winter.

If you had it in warm weather, before this winter, then take it in - you may have some break fade or some issues with your breaks.

ibleedblue82

Hey Richard,

Thanks for your response. I've only had the car a few weeks. I don't want to seem as if I'm recklessley out doing goofy stuff but I've punched it a few times. Every car is different in their reaction and maybe it's as you mentioned, tires. I don't remember this happening in other cars when on summer tires in the winter though but obviously the 911 is rear-engined.

Thanks for you input.

RRich

Could be due to the alignment and/or tires. I’ve experienced nothing but outstanding braking performance on track from my S with 19/20” wheels. On the street I've not noticed any isssues but don't typically demand much braking performance.

Richard_Wallace

I think what you are experiencing is the tires, the P-Zeros are terrible in below 40 degress. So bad on most performance tire/summer tire manufacturing sites (including Pirelli they actually warn not to drive under 40-50 degrees) - it will feel almost jittery like it is not catching. You can also get tire cracking pretty bad in cold weather. But go to Kings Porsche and have them look at it (they have better service tech than Village Porsche) , could be breaks or alignment.

Also - 14K have are your tires the originals, wondering if you also are low tread situation as well, 14K is End of Life for most performance tires (some will get more, but I average about 10-15K on most my 911's tires).

ibleedblue82

Well I'm ashamed to say that while still learning the car, I had the tires inflated to the incorrect air pressures. I was going off the 35/44 in the door jam. I now have the tires inflated correctly and for normal load. That being said a couple of nuances in response to your guys input: The car is certified but I did not see tire replacement on the CarFax. The car's build did not have satin black wheels as an option but it had satin black wheels with practically new tires upon receipt. I believe the previous owner upgraded to satin black 19/20's as the wheels were practically flawless, I don't believe they had been on the car for 3 years. I haven't checked the date code because I was waiting on satin black Carrera S take-offs I had purchased. I installed those yesterday and the build date on the tires (Pirelli's) is 01/2022. When switching the wheels size in the PCM is when I learned that my inflation pressures were way off. Considering I was running everythings several pounds over pressure lead to some of the braking quirkiness.

I have not "tested" the new setup with correct pressure to see if there is a difference. Hopefully in the next few weeks there will be some "warmer" weather to see if things will be different.

I negotiated a fairly "good" deal on the Carrera S set but I might have been better off trying to find wheels only and buying MPSS's. But it would have been a significant price increase and I believe a base car running stock tuning should be okay with the Pirelli's come warm weather.

Coming directly from a car with Signature Wheels, OEM porsche wheel prices are tough to stomach considering they are what I assume rotary forged. But I like OEM wheels on a 911 so thats why I didn't purchase another set of Signature Wheels.

Thanks for your feedback!

Richard_Wallace

Great work on digging on this more.

High pressures and cold weather you would definitely get a skating effect (jittery) for sure. You still may get some with the cold weather as these tires are just not good in cold. I have a set of winters I put on around thanksgiving every year and take off late march, just to have the car ability to handle in the cold (or snow if needed).

Just a quick side note, my McLaren and GT3 Touring have the Michelin Cup 2 on them, Those cars with those tires are just down right dangerous driving in cold weather - meaning feels like you are on ice when trying to stop when the compound become hard on the tire.

PS. Michelin PS4's are similar to your Pirelli's in cold, that is why most 911 owners have a summer set up and winter, as all season tires are really not a great option.

zachr

I don't find my car darty under high speed braking in a straight line, though I haven't done so in serious cold. If it's been below 40 for these test runs, tires might be the culprit. I wonder also if the weight distribution has an effect. The 911 has skinnier tires up front and only 40% of its weight there when stationary, but under braking the front loads up significantly, which might explain the sensation you're describing?

hogie

Theoretically it may want to swap ends under trail braking and late braking while turning. The newer cars have this pretty well under control though, along with stability control.

Corvettes are more likely to stay straight under braking due to the CG. That said, under straight braking, 911s can stop harder due to utilizing all four tires better.

My experience has also been the tires absolutely don’t work at colder temps. Never experienced what you’re describing though.

Couldn’t hurt to get the alignment checked.

ibleedblue82

Thanks to everyone for the input. To reconfirm, it was incorrect air pressure in the tires.

When younger and with only one vehicle I drove on summer tires in the winter for years. Several Corvettes and Mustangs. While never having any issues, when it was under 60 degrees I essentially "putted" around. I got used to this over several years and was always light on the throttle and easy into sweeping highway on/off ramps etc. With the C2 being down on power compared to those cars and the GT500 I had previously, I actually have a more engaging cold weather experience than in the past.

I drive the car whenver I think it would be enjoyable and weather under 50 is typically not going to qualify. Maybe in the future I'll take a look at a winter tire setup though. I wish there Michelin's were available in OEM sizes (20/21) I think they are a far superior tire to anything else in it's classification. I've always had a good experience with MPSS and assorted variations. However, I have not driven on the Sport Cups and would expect to be no help in the cold weather as you stated. There isn't a lot of tread to begin with and I'm certain it more closely emulates a hard slick in the cold!

Tompoodie

I am a bit surprised to see your comment about PS4s being poor cold weather tires.
Many reviewers specifically comment on how well they do in the cold compared to other summer tires with 1 proviso, only down to 40°.
Source: Tire Rack information page about this tire.

That said, there is no disagreement that exceptional winter tires will be formulated to have better grip then PS4s.

jlegelis

Nothing 'binary' happens at 50f sheesh, it's literally 'a matter of degrees': the car doesn't magically fly off the road at 49.5f. I love my PZeros in colder temps cuz they get all slippery and fun, while the nannies kick in to prevent me from doing anything truly silly. Great objective data - nothing surprising, just another 'dog bites man' story.

Here in Boston, my seat of the pants testing with the factory winter 992 tire/wheel setup (Conti WinterContacts) suggest grip is 25% less than the P Zeros, so now I drive like an old lady on exit ramps to avoid trashing them, and avoid full throttle which lights up the rear end in a blink. Can wait for April.

Drive it like you stole it.

Richard_Wallace

I determine cold / winter weather driving below 40-50 degrees (Specifically road temp - as your tires struggle to come up to temp when road temp is below this point). Not only is the stopping distance and overall handling effected, but damage to the tires (any pure sport/summer tire) can be damaged. Sustained driving in cold weather, specifically very cold (below 30 degree F) can cause compound cracking as well. Which is a whole other issue. Which can start to look like this after long term driving and exposure to cold...

This is particularly true when you get into the higher performance tires, etc. That is why I will not take my Cup 2s out - A.) they handle like crap in could and B.) they will start to crack even sooner than a sports tire like the PS4S, Pirelli, etc.)

I am not saying the occasional drive on a sunny dry midwestern day will hurt anything, and you probably will not notice a huge problem - if not going crazy.. However I see many people winter driving their summer tires, in below freezing (32 degrees), wet, snow, etc. This is where it becomes dangerous.

John Mclane

Before you go through the rabbit hole of alignment and tires, see if you can try a S model in the same circumstances.

My prior base C2 had a similar behavior at the end of a straight at road America, using brand new proper temp Cup2s, track alignment, TPC suspension box. The 992 S had no issues at the same spot at far greater speeds. The main difference between them is the differential (no pun).
So, before investing too much, try it out a S model, if possible of course.

Tompoodie

Totally agree that driving below the manufacturer's recommended lower temperature threshold,
Especially down to freezing is very risky... great picture.
The cracks seem to be spelling out the letters of the word, I think it says "blowout."