Please help explain tire temps and pressures??

32psi is the correct starting temperature, and is what I keep my tires at. I’ve never had my tires increase 8psi, when it’s only 86* F outside.
When I tow my boat to AZ in the summer, when it’s 118* F outside I’ll see that kind of increase. Not sure what’s going on. You could try filling your tires with nitrogen instead of air, you won’t get that kind of increase with the nitrogen.


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You should never have issue on a street. But on track it is all about managing tires and pressure/temp curve is the first basic. On my race tires cold start to hot pressure is a 10psi delta and I’m just an amateur scca club racer. A typical low intermediate occasional track day guy will do 3-6psi delta. The cup2 is a pretty good tire capable of grip that can give you a good delta so no surprise at your delta. Heat increases pressure. Weight speed corner speed brake pressure all increase heat. Tires operate at an optimize temp that is roughly equated to the set ups hot pressure. The hot pressure relates to the temp window. Rookie driving can also create increased pressure delta like over braking and sliding car too much general over driving not the car but over driving one’s skill level. This is why the first pit tools you buy are tire gauge and tire pyrometer. Once you find the hot pressure that gets your temps right it is faster to shoot for that hot pressure.

nitrogen is not the key to stable pressures. Not mounting tires with soapy water has a bigger effect. Air is 80% nitrogen. Unless you mount dry don’t bother with N2. But if you mount dry then N2 can help stabilize pressure deltas but 99% will still seat the tire bead with wet compressed air. So if you really want to do it right dry mount tires, set bead with n2, inflate with n2. That’s a costly thing to do and no street car tire shop is going to have a clue. In fact even trackside race tire guys from Hoosier and Goodyear are mounting with spray soapy water! Stick to air. There is no n2 benefit under current mounting scenarios unless you do it yourself, which I do, or are a pro race team. Even with my own tire machine and balancer filling my 2000psi n2 tanks are $50 bucks! I’m not setting beads with N2 for such marginal gains at the amateur racing level.

 

^ ^ What FBB said ^ ^ ^

Also, check your alignment. While alignment itself can/will create understeer/oversteer, an extension of what FBB noted about sliding, too much toe-in/out has the contact patch in a constant mode of sliding - which creates heat, thus higher constant temp base point.
Dealers, in general, tend to do "conservative" alignments that will induce "safer" understeer. A good race shop will give you a more neutral set-up (don't go for a track set-up for the street), if the dealership won't/can't.

If you get a pyrometer, check the temps in three locations across the tread - Inside/Middle/Outside.

 

In addition to the advice offered by others here, tire contact static friction coefficient with the road is a function of tire temperature. As a tire warms from cold, the friction coefficient increases until a peak is reached where further increasing tire temperature has reducing static grip. And the peak tire grip also depends on how many heat cycles the tire has experienced. Going too hot or too many heat cycles gives tires with reduced grip compared to peak. Sorting out the cold pressure to arrive at the optimal temp during driving needs pressure gauges and pyrometer information. The pyrometer also is used to see tire temperature profile across the tire to guide alignment for developing optimal grip for cornering and braking on each tire. Pyrometer measurements are best done rapidly when a car comes into pit without cooldown.

 

Tire air pressures, as a general rule, go up 10 % after they warm up. Ive been playing with tire pressures in all my bikes, cars, and Karts for 30 years , and its always the same, 10 % , no matter how hard im riding or driving, its really that simple, and that being whatever machine your in or on, is operating the way it should .

Big G

 

Im wondering if this has to do with the tire choice. Im not sure I’d put the Cup2 tires on an F430- at first blush it sounds like a great idea- better tires, more grip- who doesn’t like that. But I dont think the cars suspension was designed for the considerably higher level of grip the tires generate vs the PS2-PS4 type tires. Notice Im saying this is what I think, not that **I know**.

Remember, the tires are a part of your suspension. I usually do drives that range between 30 and 90 minutes in my street Ferraris and my experience is they tend to like tires set to about 32psi when warmed up. The way to set the pressure is to start out a little high and do the regular drive and pull over and using a real tire gauge- I prefer analog- set the pressures. Ive found the factory recommendation is great for someone who will do quick drives and never really warm up the tires. Also whats on the door jam of the US cars is different from whats in the owners manual- its usually higher. I think they know many owners are not going that far- or maybe cruising and not really back road driving. A decent amount of this is your driving conditions. You’ll also be able to see the difference between the onscreen tire pressures and reality.


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I can get deltas as high as 12psi on track. On street, usually 5 or 6 is the max. 8, I would check your toe--if the car is scrubbing tires it can lead to heat buildup / increased pressures.

 

I think everyone is reading to much into this, on the street, like i said, the temp goes up 10 % from cold, with that being said, it has a lot to do with personal preference and driving style, on my 328 I Iike a lot of resistance through the steering wheel, so I tend to run a little bit lower pressures than most 328 owners, I get good feed back, and great traction once they are up to the 10 % when warm, the back tires are set so I can get a proper 4 wheel slide when pushed through a corner hard , this is my driving style and I have been driving my car in the canyons with what seems like Ayrton Senna s spirit having over come me, I drive hard, and over 80,000 miles, I have never ****ed up and crashed my car, its that simple. PLAY AROUND WITH THE PRESSURES UNTIL YOU GET THE RIGHT FEEL OF GRIP AND FEEDBACK THATS SUITABLE TO THE WAY YOU WANT TO DRIVE YOUR FERRARI OR ANY OTHER CAR FOR THAT MATTER, ALL THE REST IS JUST ******** TALK, SAME WITH MOTORCYCLES . IM RUNNING 255 45 17S IN THE REAR , AND 235 45 17 S IN THE FRONT, WITH 9 INCH WIDE IN THE BACK AND 8 INCH WIDE IN THE FRONT, AND MY TEMPS ARE SET FOR MY DRIVING STYLE AND FOR THE FEEDBACK IM TRYING TO OBTAIN. TIRE COMPOUND ALSO WILL PLAY INTO YOUR DESIRED PRESSURED SETTINGS, SIDEWALL STIFFNESS AS WELL. My Conti Extreme Contact Patch rubber Im am very pleased with , I had to play with the pressures until I got it right , this is the way I do it on all my shifter race Karts.

Big G .