arowden86

I consider myself to be a pretty experienced driver. I've been racing cars/karts for over 20 years. I had my 2018 GT3 for 2 years and generally thought it was super predictable, always went exactly where I wanted it to go, but it never did well on certain surfaces. I live in Las Vegas, we have a grooved concrete highway. First time on this freeway I was trying to change lanes at ~30mph with TC off, gave it 1/2 throttle in 2nd gear and it just went completely sideways unexpectedly almost into the side of a semi truck. I was barely able to save it as it was totally unexpected. After this, I always left TC on when driving on that freeway. I noticed it flashing even over 100mph with new Cup 2 R tires. That seemed to work well enough. Then a few nights ago I was getting on the freeway, going straight, TC on, going about 90mph, barely accelerating. All the sudden the pavement changed from smooth to groved and the back end was gone, immediately. I've never in my life had a car go sideways with all stability systems on just trying to go in a straight line. I don't know if I over corrected, or if it was that I countersteered while the stability control was also trying to straighten the car out, but it was over corrected and launched the car across 3 lanes into the center wall.

Has anyone had similar experiences in their GT3? I don't know if there was something mechanically wrong with the car or if that surface was just that bad? Do cup 2 rs not work well on groved surfaces? My 800hp M5 in 2wd mode doesn't even have an issue with it. I'm really torn because I loved that car/Porsche in general, but I'm afraid to ever get another one after this experience.

Luckily I was fine, my fiancee got a concussion and is still struggling with memory/word comprehension at times. But she should make a full recovery. I know I was going a little too fast. It's my fault. But I'm just trying to figure out what actually happened/if anyone else has had a similar experience. Even at the track with stability control on I couldn't get the car out of shape. Just blows my mind that it happened going in a straight line.

konrad h1

Glad you are OK.

Here is my non-expert opinion given my experience and your description: C2R tires operate well at designed temperature. Cold C2Rs are slippery and not suitable for daily driving. How do I know this? Warm up lap on C2Rs at the track, they are worse than the cheapest street tires. On my .1 GT3 I have a set of daily driving tires, 300-400 wear rating deeper grooved tires. Yes they suck on the track and that is why I never use them on the track, for that I have dedicated track tires. But I am guessing you know this already given your experience racing cars and karts....

arowden86

Yeah, I thought about that. I live in Vegas and it was 110 degrees though. They weren't COLD. And even if they were I'd expect them to be able to go in a straight line with a little acceleration.

ninefiveone

+1. Even with regular Cup2’s I’m a little mindful of tire temp when driving on the street.

rk-d

GT3 is pretty stable. Assuming your tires were in good shape and your alignment wasn't crazy (ie severe front toe out), I'd probably chalk it up to driver error.

No offense. We've all been there. Sh*t happens.

Mthrice

Which road was it, I live in Summerlin by the 215 and Summerlin Parkway? I wanna be ready.

tqevo

how much camber did you run? on public roads the car will struggle to stay straight no matter what kind of tires if you run aggressive negative camber

arowden86

This may be the issue. A local shop told me the camber was, "f---ed" and I needed to bring it back to have shims put in or the subframe readjusted. I took it to Porsche though and they said it was, "Within spec". It did seem a bit twitchy at high speed, over 150, but never uncontrollable.

arowden86

Honestly any of the grooved surface on 215 was REALLY bad with those tires/that car. This was getting on 215 north from W Sunset Rd. by Ikea.

tqevo

The other question is how much throttle were you applying?
porsche will obviously say within spec but that doesn't tell you much/they'll say it avoid liability. for example i run -2.5 all around and it is close to impossible to not shimmy around on public roads when really applying throttle, but i have an RS so the joints are more rigid.
The first thing i always did when receiving a GT car is getting an alignment. i have seen factory alignment numbers be all over the place for brand new cars

X-PH.COM - MIKE

im sorry to hear that but glad you are okay

welikethetrack

Sounds like your alignment and camber was massively off. The fact you say your car was flashing TC light on the highway in a straight line leading up to that tells me that.

arowden86

I'd be happy if that were the case. I just can't think of anything I did wrong. I was going straight. The car should go in a straight line with PSM and TC on when it's dry, even if the tires were cold. I'm actually afraid to drive fast now because I don't think I did anything wrong. All I can think of is for some reason those Cup 2 tires hated the grooved surface. I can't believe the amount of grip they'd lose on it. They should be at least as good as a normal tire on a rough surface, but they weren't. It was like being on ice. I remember before merging on the highway, I hit it through first and second gear and it didn't spin at all in either gear.

arowden86

It would only flash TC when I was on it, on that surface. Even when the alignment was good it would do that.

arowden86

Thanks for the feedback/support. I think I'll just write it off to the tires/surface not working well together, the alignment, and speed.