I have not run any of the tires in my list. I have several friends who run the RS3's and love them. I have an e30 track car and run Dunlop Star Specs which I love, but they dont come in a 19.

Interesting. I have never heard that. I am glad you said so cause as you can see, several of my options have the fronts larger or equal size to the rears. Do you know why this is?

I dont think that would make any difference as long as clearance is okay and OD is similar. Do you have a source for that info? Thanks,
Matt

 

Well, since PDCC's job is to keep the car level in a corner, as long as the weight of the wheel/tire does not exceed the OEM, I would think it should be ok. I have driven on the mountain road and the onboard G meter showed a max lateral acceleration of 1G without any issues, the car's handling was excellent, and I am going to Thunderhill this weekend, so I certainly will know how it works at a higher speed.

Besides, the TPMS can accommodate 3 sets of wheels, 20" summer, 20" winter, and 19" winter. By logic deduction, PDCC should be able to work with 19" wheels as well.

 

I would have gone with the Toyo Proxes R888 for dedicated track tires if I were you. They're DOT legal so you can drive on them to/from the track so you don't have to worry about carrying an extra set of wheels and tires with you. Did you consider these as an option? Next time around you definitely should. The PSS are definitely not a good choice for a dedicated track tire. Really no well-rounded street tire is. After years of tracking my cars, I finally went with the R888 for exactly these reasons.

Next year I finally won't have to worry about it since my Raptor will arrive in a couple of months and I'll join the club of those fortunate enough to be able to trailer their car to the track! My old '77 F-150 that's heavily built for off-roading just isn't up to the task of trailering a car 2 hours each way. (Well it might be up to the task but I'm not!)

 

Scott, I appreciate the recommendation of R888, and I think I will switch to that next season. I only have 1 DE event under my belt, so I am still pretty green, and good predicable street tires like PSS would be a good starting point for me, I thought. After my first DE I decided to make 2 modifications to my car: lighter wheels and ATE blue brake fluid.

One question, though: although R888 is DOT legal, wouldn't it wear excessively on the highway? It's about 200 miles one way to Thunderhill raceway from my home, and I do not plan to get a trailer yet.

 

Excellent choice going to a higher quality fluid for the track.

Re the Toyos, I've spoked to a board sponsor who we all recognize as very knowledgeable on tires (but didn't ask his permission to use his name). He said the Toyos are approved for street use, that you can use them on the highway with no problem, and that if you use them for occasional track days and daily driving on highway you can expect ~75% of the life of an OEM tires or about 10k miles.

 

Thanks for the info, KonaKai.

 

Sure thing.

And apologies for hijacking the thread a bit but I should mention: I ran the original OEM fluid for the first 5 track days since the car was only six months old and 5k miles.

Then I did a flush with ATE Blue before my last event (3 day at Pocono Raceway last weekend) and was very thankful I did when I roasted my rear brakes. That much heat can't be safe for the brake fluid. So, I'd recommend to anyone who tracks the 991S at all, certainly by the intermediate level of driving, to make sure they use a track-use fluid like Motul or ATE. Cheap insurance against an obviously almost guaranteed incident if your brakes fail on the track.

Re the tires, I think this thread has convinced me to buy the Toyos:
1) It should save money over the long term. In my experience, once a season or so I overdrive the street tires and damage 1 or 2 tires. Given that the Toyos are cheaper and more durable under stress, I figure that's a good investment.
2) The extra grip will be something new to try and experiment with. Always good to mix it up, keep it fresh... and get faster .
3) From a safety perspective, I think higher grip generally means more safety (traction = good ).

Downside is that extra grip will work the brakes even harder. How much harder I'm not smart enough to know. I'm doing a 2 day at Watkins Glen soon and that will be a good test to see if the overheating was an anomaly from the config at Pocono North infield. I'll let you know but again if I could offer some humble advice to guys tracking the 991S it's to consider pitting in mid-session, at least at first, to check on your brakes.

Possible other downside: At least in the 997 manual, I remember reading an explicit disavowal of track tires (r-comps) by Porsche. They say it's not suggested or approved, which suggests some risk to warranty and more importantly it's possible that the rubber bushings, PDCC tolerances etc. aren't designed to work as well with those levels of grip. You're also going from 20" wheels that Porsche had in mind when they tuned the S to 19". I don't think Porsche figured on too many guys buying an S and putting on 19" wheels. Not a huge difference but the more complicated these cars become, IMO the more potential for unintended consequences when you alter the variables. I know it's been mentioned that the TPMS has settings for 19" winters but do we know if that signals (undesirable) changes to the ECU, throttle response etc. since the computer now thinks its cold outside?

Then again, Serge (ATL) has done and enjoyed many mods and I hope he never stops because I've definitely enjoyed watching it unfold.

On balance though, I think the pros win out over the cons here. My first mod - the pandora's box has officially opened for business.

Best,
Lee

 

Lee, I agree with pretty much everything you wrote. The only thing is how well R888 performs in the wet. Our winter season will bring quite a bit of rain here in California.

Read the same warning regarding R compounds, we will have to see what would happen. When I took my car to the dealer for oil change, brake fluid flush, and fixed a couple of recalls, they also did a check on the whole car and noted that my tires not Porsche approved N tires. Wonder if that will go into my service record?

I know it's a slippery slope when you start mods...

Still eagerly awaiting your research finding into DIY brake pad change.

 

I spent this Sunday morning swapping the wheels, and also use my bathroom weight scale to check the actual weight of OZ wheels vs OEM Sports Design wheels. Here's the result:

OEM Sports Design front: 48.2 lbs
OEM Sports Design rear: 62.5 lbs

OZ Superforgiata front: 41.8 lbs
OZ Superforgiata rear: 50.2 lbs

 

I spent this Sunday morning swapping the wheels, and also use my bathroom weight scale to check the actual weight of OZ wheels vs OEM Sports Design wheels. Here's the result:

OEM Sports Design front: 48.2 lbs
OEM Sports Design rear: 62.5 lbs

OZ Superforgiata front: 41.8 lbs
OZ Superforgiata rear: 50.2 lbs

Are these weights for wheels plus tires?

 

I don't know the answer to ^^^ but to raise a related issue, do we know how the strength of the OZ's (or any other wheel) compares to the OEM? In my experience, the moment will eventually come where you'll clip a curbing awkwardly, maybe 2 wheels off, whatever, at speed and all that will matter to you is how your wheels hold up, not the 10 pounds you saved. It's a DE not a race after all.

There have been numerous videos posted here in the past where you see the rim break on awkward contact with curbing. I'm not drawing any conclusions on OZ or any other wheel vs. OEM but IMO you have to at least consider the issue.

 

Wheel and tire together.

 

I don't that either, but OZ has a good reputation, and the Superforgiata is forged, so should be pretty strong and durable. I'll know after this weekend DE at Thunderhill.

 

A quick update, just came back from 2 track days at Thunderhill.

The PSS did pretty well, progressive when traction was lost, and gave plenty of audible warning. The car's on-board G-meter was registering a max of 1.28G on lateral acceleration, and 1.2G on braking.

However, the pressure at peak temperature must be managed. First day I was keeping front at 32~33 and rear 34~35 while hot, and I had a good day. Second day the weather was cooler, and I was not as aggressive in reducing the pressure, and had a bad session where the front tires were squirming under braking and pushing while on the line, a bit scary. When I checked the pressure right after coming off the track, the front was almost 40, and rear over 40. After I reduced them, they felt better in later sessions, although not matching the peak performance of the first day.

I feel that street tires like PSS are great on street with aggressive driving style, but high temperature at track still make them squirmy. Looks like I might need to invest in a set of R888 or Nitto NT01, from talking to the Porsche drivers at the track.

And the difference in tires made a big impression on me because in my beginner's group, there is a brand new Mustang BOSS that was simply faster than me on corners. At straightway the acceleration of my car and his were about the same. I learned that the Mustang is made for track, with 444HP V8, 3600lbs curb weight, and 255/40/19 front, 285/35/19 rear Piralli Corsa tires. I have 245/40/19 front and 295/35/19 Michelen PSS, and I could not keep up with him at corners.

Slippery slope, indeed.

 

Anyone else using Superforgiata wheels, especially in 20s?