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+--- Thread: Seeking tire advice... (/showthread.php?tid=4029)
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Seeking tire advice... - cmac - 09-05-2015
Guys,
I've been running on Pilot Sport Cup 2 tires for the last three events I've done and I'm thinking I can get another weekend out of these but wanted to try to get an opinion from someone who's run through a set of these.
I've had a total of 9 days on them and approximately 24 heat cycles. Last event was Thunderbolt and about mid-way through I was ready to say they were shot. I was sliding around quite a bit, but it was really hot. After dialing down the pressures, they performed really well through five run groups on the last day.
Anyhow, there seem to be many opinions online about these tires. One guy says they last forever, another says they're good for 20-30 heat cycles. I've got what seems to be OK tread left on one side and semi-OK on the other. Photos below.
Opinions?
Thanks in advance,
-Corey
RE: Seeking tire advice... - MikeKling - 09-15-2015
Corey,
The heat cycles on all these tires does vary on many conditions. The biggest variable is your driving level. As speeds increases so does what we expect these tires to do. We drive in a circle clockwise with our friends. So the left side bears the most load and thus highest temperatures. The best way to extend the tire's usefulness is to rotate them side to side. Some tires are unidirectional and can be "flipped" on the rims to get one last event on them. As you continue to use them longer, jack up that car and tale a good look at them at the end of each day. Make sure they aren't corded. Like many activities in life, the feel you get tells you a lot about what's going on underneath you. Cars have a way of telling us when something isn't right. We just have to learn how to listen.
RE: Seeking tire advice... - 997S22 - 09-16-2015
Not advice but sharing experience - I ran the prior Sport Cups on 997S and 997 GT3 for 5+years. Both cars had significant negative camber for track use. Typically before trailing front camber -2 (when trailering ran around -3.5) would still roll tires under while cornering and wear outer edges. Before outer edges were destroyed I had tires flipped on wheels to balance out the wear. These tires are assymetrical with suggested mounting as in your picture. However the tread design is not particularly senstitive to mounting direction - especially on dry road/track. Look at the deep chevron tread design of a Hoosier or Pirelli Wet tire and you can envision how mounting backward will pump water under the tire in the wet - the Cup tread will not do that. I ran them until approaching the cords - little to no tread left. Obviously if you are driving the car to the track you need to be much more conservative. You need 2/32 or more tread left to negotiate even moderate rain on a drive to or from the track. If you are trailering or carry a 2nd set for street use that is not as big an issue. These tires are way less sensitive to heat cycles than Hoosiers, which are less sensitive than true slicks. With nearly 300 track days and 4 years of racing, in my experience heat cycles matter little for street tires. Hoosiers lose grip more noticeably with heat cycles, but for DE I run them almost to the cords - racing I use them 4-8 HCs than save for DE. Slicks I treat like Hoosiers but they are far more sensitive to HCs and fall off more noticeably. Used slicks are particularly bad until they warm up after a few laps or on cold or damp days - so require extra caution those first laps or a swap to newer tires. Hope this is of some help to you.
RE: Seeking tire advice... - cmac - 09-17-2015
Great advice guys, thanks. I also got a couple private messages prior to last weekend's event which confirmed that the PSC2's tread wear is much more of a factor than heat cycles...
The tires held up pretty well, though I did lose one session on Sunday afternoon after they gave out. (See photo.) If I had swapped L/R on Saturday I would probably have been fine to finish the weekend, so that was a lesson learned.
The consensus seems to be I need more camber than my factory setup can deliver to prolong tire life, so I'll be looking at that sometime soon...
RE: Seeking tire advice... - cmac - 09-17-2015
Post-event tire condition. (Passenger side from Pocono SE)
RE: Seeking tire advice... - 997S22 - 09-17-2015
Yes some extra camber will help reduce this wear on outside edge. If track only car keep adding negative camber until you get fairly even wear on track days. However, if you primarily drive on street you will find you wear the inside edges while driving on street with extra camber, so you don't want to over do it - street driving is not aggressive enough cornering to roll the outside edges under like you do on track. For dual use street/track car you probably want -1.5 to -2 front at maximum. Track only can go as much as -3.5 front with your tires, as much as -4.5 front with slicks. Rear camber will be somewhat less - typically 1/3 or so less than front - depending on several factors, particularly how wide the rear tires are relative to the front - wider tires generally require less negative camber.
Since for street/track use you have to be modest with the negative camber, dismounting and flipping tires on the wheels before the outside edges wear too much, to balance out the wear, is the next best alternative to killing the tires prematurely by wearing off the outside edges as in your picture. For example if you find tires tend to last 4 events, flip them inside out on the wheels after 2 events.
But it is also a balance with the level of your driving - the faster/harder you corner the more you need extra negative camber to keep as much of the tread as possible flat on the track while cornering, and the more evenly your tires will wear on track with that extra camber. With track only cars running lots of negative camber, if you don't corner hard enough to roll the tires to use the negative camber you have, you will not have the tread flat while cornering and will lose grip. For that reason it is best for most to increase the negative camber progressively as they progress from green to blue to white etc., unfortunately with the high cost of full alignments that is not inexpensive if you are progressing rapidly. But most drivers do a limited number of events per year so the progressive approach works well for them. For street/track cars this is not generally an issue as you are limiting the negative camber to avoid destroying the inside edges while street driving.
Again this is not advice but sharing what I have learned through experience.
RE: Seeking tire advice... - Bill Lehman - 09-17-2015
Corey, For years on my Cayman S I have been running -3.0 F and -2.5 R camber, 0 F toe 1/16" total rear toe measured at the wheel rims. My car is still street driven and I don't notice adverse wear. You need GT3 type LCA to get the F camber. I get the R camber with stock LCA but my car is lowered which adds -camber.
RE: Seeking tire advice... - Phokaioglaukos - 09-18-2015
Some really good advice here. I plan to attend our SP DE and will have my memory pyrometer with me, so ask to borrow it to seem how your tires are working. It does left, center and righ on each of the four tires and give you a display that is easy to read. If the temperatures across the face of each tire are not close then you may have some adjustment to do.
Comments above about the balance of street and track driving fully applicable!
RE: Seeking tire advice... - MikeKling - 09-19-2015
I always forget my memory pyrometer.
RE: Seeking tire advice... - Bill Lehman - 09-19-2015
[attachment=3826]What were we talking about? Lacking a memory, here's a form I use to record temps.