19" wheels and slicks on an 812?

Stock the car comes with 20" wheels so 19" wheel is only 1/2" drop from the center point excluding any tire differences.

 

Not sure you are going about this the right way.

Let's get the wheels themselves out of the way. You can fit 19" wheels on the 812. So that in itself is not the problem. The issue lies within what you wish to accomplish.

While the 812 is an incredibly capable car in every way, I very much doubt that the suspension is capable of handling slicks. A car like the 488 GTB is not capable of this without modifications. Too soft, too little camber which result in tyres that either skip or roll over. A car like your GT3RS or a Pista is much more capable of handling such a tyre as it was set up for it. When the Trofeo R tyre came out, people thought it would be a great upgrade over the MPSC2, but it was quickly found that the suspension on stock 458 and 488 cars were not up to snuff. Some got around this by adding a ton of camber to prevent the inside of the tyre from lifting, but it was a bandaid - even on the 458 Speciale. Stiffer springs were needed to keep the high grip tyre with a very stiff sidewall in proper contact with the surface. This has through all my years of being a car nut and a tyre geek, been the biggest and most common error I've seen. Grip that overpowers the suspension.

If I were in your place, I would go about it in another way. You say you want to lower the car for aerodynamic grip. Well, if the air you remove from under the car translates DIRECTLY into downforce, yes this could be the result. However, when you lower the car a lot, you also take away the diffusers ability to work, as there's less air going across it to create the venturi effect. Add to this that the air now going above the car may just be displaced to the sides and up, but without adding actual downforce. One thing Ferrari has worked very hard on, is reducing lift from air going under the car. This is a major priority, not only because Ferrari hates big fins and spoilers, but also because a street car needs some ground clearance. There's a very good chance that you migh do more harm that good in terms of aero grip from excessive lowering. Can you gain a bit? Most likely, but that sweet spot is probably found at a fairly moderate amount of lowering. 25-30 mm perhaps. You need some air under the car for that aero to work, it's not a real aero race car like a GT2 Ferrari.

When you change the tyre circumference as much as you would have to do for a 2" drop, i.e 4" diameter change, you actually lose a lot of thread patch. What good will more aero do you if you lose a lot of contact patch? Add to this you get a lot less surface for heat dissipation. It's a poor deal all around with such a big car.

If I were you and wanted to try some seriously sticky rubber on a lowered 812, I would go about it completely differently.

Get some stiffer springs from Novitec for a start. Then lower the car about 30 mm rear and 35 mm front.

For wheels and tyres, I would pair MPSC2 R up with a set of Forgeline GS1R Open wheels. 265/35R20 front and 325/30R21 rear on 9.5x20 and 11.5x21.

Get the car cornerweighted and move the bias slightly towards the front to co.downstate for the slightly narrow front tyres, and use the springs and collars for proper lowering. Then star adding camber, because that will be needed with the sticky rubber. No idea how much as all of this would be purely experimental, but I would use the Pista camber settings for a start. It will not be perfect but I'm sure it will be a suitable place to start.

At any rate, don't use very small wheels cor lowering, especially without proper data on the aerodynamic properties of your car. My guess is that all you gain is a bunch of tyre wear not to mention a hell of a lot of wear on your diffuser, side skirts and front splitter.

Stick with a nice diameter but lower with stiffer springs and go from there.

But hold your horses...

Personally here's what I'd do to keep it simple, usable and drivable on and off the track.

TdF PZero Corsa 4 rubber on lightweight Forgeline wheels with stock offset - perhaps adding 2mm rear and removing 1mm front, for just a hint more turn in and oversteer. But removing too much offset from the fronts to push them out even further, will mess up the steering geometry. Removing front offset or adding spacers screw up the roll center completely. It might look cool, but it does all **** for handling.
Novi springs with only 15mm lowering all around. This mainly for the added stiffness for the added bite.
Pista spec camber and corner weighting.

You can do all the previously described things, but my bet is that the last suggestion, my personal choice, will work the best and cause you the least headaches. Once you have gotten the "simple" setup right, then you could try the more oddball stuff. But trust me when I tell you that adding 19" wheels with rubberband profile slicks for tyres, will not do anything good.

 

Co-Pilota has given you sound advice. The Novitec springs are close to the VS setup and will remove the dive you mention. The height, balance, corner weighting and camber calibration can be set by a suspension shop familiar with F12/812. Might want to address brakes/fluid if you like to track these cars. Good luck and post your results.

 

The Pirelli PZC4 fair quite well. Unlike the regular PZ4 it handls heat well. Not sure what to make of your thoughts on Dunlops. My experience. Which I know I share with some RSR instructors and Porsche drivers, is that the MPSC2 is the overall better tyre.

The PZC4 TdF spec tyre was designed for a car with the power and weight of the 812.
Compound is softer than MPSC2 but harder than Trofeo R and MPSC2 R.

The 812 and F12 you have are from the factory set up very differently. The F12 feels to me like it lacks damper - or has too high spring rate. Depends on how you look at it. But it can get really busy in the suspension and bounce a lot sometimes. The 812 is much more planted in this regard, almost opposite in fact. When I say opposite, I say this because one can really feel that the 812 has quite firm damper valving. Not to the point of making the suspension slow, but there's a lot of damper for the spring. This I definitely prefer over a somewhat busy and slightly nervous chassis setup, which I think is a bit of a letdown of the F12. It's a great car with a lot to offer, but the damper/spring rate is off imo.

This added damper of the 812 really brings up an interesting point. It means that the car has the ability to handle a firmer spring. In stock form the 812 already squats and dives less than the F12, and with springs, good rubber, camber and corner weighting it will become quite the 800 PS front engined weapon.

 

So what kind of lap times did you run in the 812?

 

Wow, I ran PZeros on my 488 and 991tts, never had that kind of damage. I usually got a couple of events out of a set of tires. It must have been really hot on Saturday but I was at the one in July 2018 and it was over 100, still didn't have that kind of damage. You really were over pressure. I always ran starting at 30 and 28, by the end of a session they were at 45-50 and I would bleed them back down. So most of my wear was on the outside.

 

I get the same on both a Pista and 488. The.MPSC2 last maybe three 3 hour sessions, and then stock pads are gone too. One of the issues is the lack of camber which creates a ton of understeer. On a 18c day the Pista and 488 tyres spike in the low 90c and I have seen pressures spike above 2.7 bar. I think like all road going Ferraris, the wear in the pic above is just a result of the understeer and low camber our cars have. And on an 812 if you run stock tyres on track, forget about it. They boil after three laps on a twisty track and then they are shot no matter the amount of tread left. Regular PZeros and MPS4S tyres are simply not track tyres. An 812 on track needs either the TdF wheels or an aftermarket set of wheels with GT2RS rubber on it.



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When you get your new springs in, seriously consider getting your car set up for a bit more track stuff. You don't have to go crazy, but two things you should do.

Add half a degree of camber to each front wheel.
Then get the car corner balanced and move the weight forward 0.5%.

This will kille some of The understeer, but it will also put a greater demand on you as a driver. It will not be dangerous, but the safety that helps you as the front starts to slide will be gone. Instead of a car that starts to steer and regain control if you apply the brake during an understeer skid, a well balanced and more neutral car will swap ends. As a performance car it will be much less brutal on tyres as the car will be much more willing to turn and stop, and it will also be more precise and nimble in your hands, but it will not save you and help you the same way a street car with a ton of understeer will. But if you use the ESC and keep yourself in control, it is a great way to enhance the car. Just remember that you might need to take a step back and relearn the cars signals a bit. Additionally you can of course take it from toe out to toe in. This will make the response slower and less darty.

But if you really want those tyres to live, you need to kill some of that understeer. And lastly, just keep dropping that pressure as it climbs. If you run the TdF set, try 2.25-2.3 bar hot squared and go from there. Just bring a small 12v compressor if there's no shop air. Easy.

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Hehe, yep let it all hang out

Would you mind sharing your alignment specs?

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Hope you got the front lifter. Looks pretty good. Is that the ATT conference center in the background?

 

Looks fantastic.

If you want R888r, you can drop to a 30 series tire for stock wheels (will lower the car). The front will bump to 285.

 

That's not bad for OE pads. They are not made for the track. Note that you cannot go lower than 3mm in thickness, so 2mm left. Contact Vivid Racing and ask if they have any more Pagid RSC2 pads left in stock. Unfortunately Pagid has discontinued the 4580 and 4581 pad shape in the RSC2 compound, but there are still examples out there. They are longer lasting and more of a race compound than the OE pad.
As an alternative you can look into getting Surface Transforms CCST brake discs. Aside from offering all the "regular" CCST disc advantages, they open up the ability for running the Pagid RSL1 race pads.

Not sure toe out on the 812 rear is a great idea, but looking forward to hear about it

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Very interesting comments !

On my F 12, i ve 4 brand new shock absorbers withe the new reference product for the front, 4 TDF springs 35 % more rigid than stock s F 12,
TDF ground clearance & alignment.
Concerning the tires, i installed news Bridgestone S007 , not a half slick, but very near.
The complete set up change everything, not the same car !!!