misterbeverlyhills

Hi Pete,
Can you tell me what the best track tire pressure is for my 1973 911 coupe? I have 205x15x7in all around with Fuzion Z tires. I usually run RA1s all around on track days but I don't want to drive to Willow tomorrow with all the rain on RA1s.
Looking for front/rear cold tire pressure recommendations knowing full well that is a loaded question and to each his own. A starting point would help as I hate futzing with tire gauges all day.
These Fuzions have completed a couple of DEs and front outer edges are surprisingly worn, more than any other part of the tire, skidpad with my daughter, round and round may be the cause but could it be pressure too?
Thanks in advance
I included a photo so as not to get scolded.

Marc Bixen

Sorry Pete didn't get back to you we tried to get him to respond but he must be unavailable. At Red Line our basic track set up is to achieve a tire pressure of 40lbs. HOT, immediately after you come off track on a hot lap. Try to avoid a complete cool down lap, stay on it until turn 9 come in and check pressures ASAP. Chances are if you're a driver that knows your car and track well, on a cool day like today 1st session start around 34lbs. COLD then check immediately after. Bleed them down, or increase them to 40lb. . Again ASAP. By mid day track temp in the 70's- 80's cool by Willow standards, you'll need to bleed the pressures at least 3-5 lbs. Remember 40lbs. hot. Now keep a note book, record track temp during the day. Tomorrow morning recheck your pressures and record them. This is your refrence starting pressure for next time. In the morning start about an additional 3lbs. for a cold track,then bleed down. I hope this info helps. Fine tuning comes after that point.

Peter Zimmermann

misterbh: greetings! Sorry I missed your post, I was pretty much unavailable during the weekend. Marc's post above pretty much says it all! The only other thing that I can offer is to start the first session at about 32F/34R cold. Then follow what Marc said. Obviously this will be for next time!

Ed Hughes

I'm no expert, but I will say that all tires are different. If I get my Yoko R's up to 40psi, they will have less grip than if I keep them under 35psi. Having said that, my old MPSC's loved heat/pressure.

Amber Gramps

Marc, how are you? Glad to see you. It's about time.

Folks, if Marc says it.....I'd go with it. He's the only guy I know that can out Peter Zimmermann Peter Zimmermann.

misterbeverlyhills

Thank you, good to hear from you Pete, Had a blast at Streets of Willow and turned some good times in the 73. John from Otto's made a point to send you his best, he was instructing.

mck911

What are the sidewall sizes of your tires? Just curious as I'll be running a similar set up on my 74.

misterbeverlyhills

I am running 225x55x7 Fuzion for farting around or wet weather and 225x50x7 Toyo RA1s for the track.
Thanks,

rusnak

Wow. That's some heady praise. Welcome, Marc!

Amber Gramps

....and to think I went easy on the guy. To enter his shop requires an agreement not to look at or touch the car on the right and please don't tell anyone about the car on the left.

If spending your weekdays wrenching on exotic Porsche's wasn't enough to really mess with your head, Ferrari puts him in the pits on the weekends....literally.

rusnak

Dis-a Fer-rarr-ee scuderia. You-a show-a mahyee car-a to noh cus-tomerzz....Ci?

Ed Hughes

I still stand by my statement that different brands of tires will like different pressures.

Peter Zimmermann

Absolutely! That's why I recommended above to start off with conservative settings (32F/34R), just to see how they respond during heat cycles. If you're second or third lap out is the quickest of each session you have work to do (just one reason why Marc's advice to keep a notebook is so good)! From personal experience most of the "street" tires that I've driven on have felt better up near 40 lbs, but I can remember a couple of sets that certainly performed better at lower temps.

Ed Hughes

Indeed, I take notes every track event on cold PSI, hot PSI, weather conditions and any pertinent handling notes.

Now, if I can make enough money to hire some crew so I can pull in to the hot pit, and have them measure temps across the tire, record my times, keep the car running well, fix broken stuff, etc, I'll be doing well!!

Marc Bixen

Doug,
I'm blushing. Thanks for the complements, working for P.Z. many years certainly helped. As you know my dad was racing a 57 Speedster when I was born in 61, so I guess you can say I've been around Porsches for ever. That said I have had no more enjoyable time then the years I spent working with Pete.
As for Ed's comment, I fully agree that different tires, different track surfaces, etc. make a difference hence my final statement " Final tuning comes after that point". My earlier post was a starting guideline based on working a number of years in racing alongside one of the finest engineers in Champ Car and Prototypes. Personally I run at 40/40 hot on my 1991 RS America with BF Goodrich G force TA's 205/17 & 245/!&