[pepinozaur]

Guys what about a crazy, crazy setup.... I was looking to maximize my 10-12" Finspeed setup and wondering about the following slicks setup:

- 285-650-19 Pirelli from Senna GTR and P1 GTR in front. I dont have now the specs, but I assume is a 26.0-26.1" tire like the narrower brother, the 255-650-19 which is designed for only 8.5-9.5" wide rims.

- 315-705-19 Pirelli (and not the 325 used on same Senna GTR and P1 GTR) as the 315s are used for 11.5-12.5 rims and Senna GTR with its 325 slicks runs already 13" wide rims.

- 27.75/26.1 = 1.063 That should be OK



I am having two potential problems:

1. Are the front tires too wide? 285 on 10" should sit nicely, but is it too wide or not? Assuming the 265 Nankang/Trofeo are perhaps in the 272mm wide terriotry, maybe they arent, idk...

2. Are the rear tires too tall? At 27.75" or 705mm they are at a limit, idk if on track use we might be able to run them, also I have Novitec springs set at maximum height, but still the car should be perhaps like 5mm lower than OEM.

What do you guys think?

 

[ian.mcloughlin]

"285-650-19 Pirelli from Senna GTR and P1 GTR " - I can't find these tires anywhere. I get my Pirelli DH tires from Home - Frisby Performance Tire and most seem to have Ferrari challenge stickers on them but those may be perfect if I can't get the 295/680/19's to work without rubbing. I think it's a great idea.

So I have some good news,

I was on track all day last Friday fine tuning & swapping shims, spacers, etc...

With renaissance speed shims, -3 degrees of camber in the front, -2 in the rear, 11mm novitec spacers in the front & 15mm spacers in the rear, on finspeed F10s 10x19 12x20 ET38 in front and ET25 in the rear before the spacers (I had a 20" F10s made for street use) w/ the hoosier R7s P295/30ZR19, P335/25ZR-20, my lap time at big willow was 1:24 With gyrodisk + Cobalt XR1. While it's not an incredible time, I have a lot to learn on this particular track still.

That matches my time down to the second (a few ms slower) on the pirelli DH slicks on the finspeed 10x19, 12x19 255/650-19 (fronts), 305/690-19.

For reference with the OEM McLaren wheels & goodyear 3Rs (265/315), I am around 1:27.

With Trofeo Rs on those same wheels, I'm around 1:29 for some reason. Even worse, with Trofeo Rs, after a couple of heat cycles, my times are 1:32+ and they start sliding all over the place, even under ideal tire temps & hot pressures around or just below 30psi. The goodyears hold great lap times for multiple (2) track days as do the Pirelli DH tires (3 track days).

The only issue with front tires this tall/wide (P295/30ZR19 R7s) is that when the nose is lifted (stock suspension) I can't turn the wheel more than 90 degrees or the wheel will rub the front of the door. With the car lowered though, there is no rubbing, even under full suspension load and hard cornering. Basically I only drive the car straight when lifted, to drive onto a trailer. It can be quite embarrassing to keep raising and lowering to make hard turns, but after taking them off and examining, there is 0 rubbing during track use on the stock suspension + -3 degrees of camber up front.

My 295/680/19 315/705/19 Pirelli DH tires just arrived which is my next test, I'm getting them mounted next week to the 19x10,19x12 ET38 in front and ET25 in the rear finspeed wheels and I'll report back. They are a tiny bit wider and taller than the R7s, but it doesn't look like it will be an issue with these wheels so long as I continue to use the spacers and have enough camber.

Thankfully the novitec spacers are very high quality, and come with extended lugs (they did it the right way). I've had no issues with them so far. In the rear we can actually go much wider if we get wheels made with a different offset (I worry about going any wider with spacers), but in the front, I'm not sure we can ever go above 295 without removing part of the door. It's some sort of fiberglass so I don't think we can even roll it. It's a difficult design to work with.

The ODs/stagger looks ok for ABS/TC so long as I can get them to fit without rubbing. I'll report back in 10 days or so once I've had a chance to test these 295/680/19 315/705/19 Pirelli DH tires. My hunch is these will be king for the 720s... but they cost a fortune & take me 1-2 months to get.

 

[pepinozaur]

Good stories and congrats for your new record times, fitting the 295 Hoosiers in the front is sweet.

Yes please report back about the 295/680/19 fitting in the front, but that is a HUUUGE tire, as I read the specs it runs at 26.9" tall, so close to OEM rears .. LOL, I just can't see how that would fit in there, but I keep my fingers crossed for you. On the other hand, you can still keep the 255/650/19 (which is actually more of a 660 tall tire) and mix them with 315/705/19 and see how it goes.

Maybe also try to run fronts on really low pressure so you can save a bit from the rolling diameter. I am glad you trying those, I will try to find those Pirelli MC only 285 and report also back here.

Specs I have discovered so far :
Official name: 285/650-19TLP1-GTR SLICKMC
Compound: MC - not DH or DHC
Price aprox 520Euros+VAT so like 750$ including taxes, without shipping to US

If you will be able to fit those nasty 295/680s, then there is no advantage to get the 285s from above.
Also I have been last weekend to Dubai24H Endurance series, the 720S GT3 runs 300/680 fronts and 320/710 rears, so pretty close to this setup. The Hankook 710 is actually more of a 705 tire, but their 680 is a real 680 and it runs at 674mm in R18 and 677 in R19, also hankooks are like +20mm wider from the rating above compared to Pirelli which rates already the section width and not the tread width like hankook, michelin and others.


Ona funny note, and this might save us a lot of time and effort as we can test various setups, I have the same Rims with the same ETs as yours, also the same spacers 11/15mm Novitec, same Giros etc.

My car runs now Novitec springs at their max height position and having some custom made shims, we were able to run only -2.2 camber or so, I run a bit of Toe OUT in front, TOE IN in the back, caster a lot more than stock.

 

[ian.mcloughlin]

Good stories and congrats for your new record times, fitting the 295 Hoosiers in the front is sweet.

Yes please report back about the 295/680/19 fitting in the front, but that is a HUUUGE tire, as I read the specs it runs at 26.9" tall, so close to OEM rears .. LOL, I just can't see how that would fit in there, but I keep my fingers crossed for you. On the other hand, you can still keep the 255/650/19 (which is actually more of a 660 tall tire) and mix them with 315/705/19 and see how it goes.

Maybe also try to run fronts on really low pressure so you can save a bit from the rolling diameter. I am glad you trying those, I will try to find those Pirelli MC only 285 and report also back here.

Specs I have discovered so far :
Official name: 285/650-19TLP1-GTR SLICKMC
Compound: MC - not DH or DHC
Price aprox 520Euros+VAT so like 750$ including taxes, without shipping to US

If you will be able to fit those nasty 295/680s, then there is no advantage to get the 285s from above.
Also I have been last weekend to Dubai24H Endurance series, the 720S GT3 runs 300/680 fronts and 320/710 rears, so pretty close to this setup. The Hankook 710 is actually more of a 705 tire, but their 680 is a real 680 and it runs at 674mm in R18 and 677 in R19, also hankooks are like +20mm wider from the rating above compared to Pirelli which rates already the section width and not the tread width like hankook, michelin and others.


Ona funny note, and this might save us a lot of time and effort as we can test various setups, I have the same Rims with the same ETs as yours, also the same spacers 11/15mm Novitec, same Giros etc.

My car runs now Novitec springs at their max height position and having some custom made shims, we were able to run only -2.2 camber or so, I run a bit of Toe OUT in front, TOE IN in the back, caster a lot more than stock.

The 295 R7s were 26.1" Overall Diameter according to tire rack, & I managed to get those to fit, fingers crossed 🤞

I had to use the shims. Currently I have -3° front and -2.5° rear camber, with ~ -.10° front and ~ .4° rear toe. I can't remember where my caster is though. I agree with you 100%, the slightly negative toe in front makes the steering feel more responsive. I suppose the downside is how it chews the tires.

That is perfect! It sounds like we will have exactly the same setup aside from the camber & your novitec springs. I'll let you know, for now they are just taunting me!

 

[Gary(SF)]

With renaissance speed shims, -3 degrees of camber in the front, -2 in the rear, 11mm novitec spacers in the front & 15mm spacers in the rear, on finspeed F10s 10x19 12x20 ET38 in front and ET25 in the rear before the spacers (I had a 20" F10s made for street use) w/ the hoosier R7s P295/30ZR19, P335/25ZR-20, my lap time at big willow was 1:24 With gyrodisk + Cobalt XR1. While it's not an incredible time, I have a lot to learn on this particular track still.

Makes RP's time in a stock 720S of 1:21.75, on Corsas, seem even more other-worldly.

 

[ian.mcloughlin]

Makes RP's time in a stock 720S of 1:21.75, on Corsas, seem even more other-worldly.

I know, me cheating using slicks can't come close to RP! I also have lighter Senna seats (for the MSO roll bar & harness).

I've studied his driving line a lot. We carry similar speeds within a few MPH on each corner & I follow as much of his driving line which I can see in the video. I can't figure out how he holds so much speed through the corners on corsas!

A small part of it must be that "magic, new tire first lap". I've seen him mention in a few videos that he is up to 1 second quicker at big willow with brand new pirellis for their first magic lap during only their first heat cycle. Even still, I'm cheating using slicks & can't come close.

On this track the breaks do get very hot. The XR1 pads are spongy for me after just 5 minutes on track until they cool for a lap & then they are back to an aggressive bite.

One thing I have left to try, is to go back to the OEM carbon break setup to see if it helps buy me another second or two. I switched to the gyrodisk setup too early on to have recorded the time difference (if any).

I've yet to see any other road car do better than 1:28 there in person. He is just an incredible driver. I can't imagine what his lap times would be driving a 720s on slicks.

 

[AWH]

I know, me cheating using slicks can't come close to RP! I also have lighter Senna seats (for the MSO roll bar & harness).

I've studied his driving line a lot. We carry similar speeds within a few MPH on each corner & I follow as much of his driving line which I can see in the video. I can't figure out how he holds so much speed through the corners on corsas!

A small part of it must be that "magic, new tire first lap". I've seen him mention in a few videos that he is up to 1 second quicker at big willow with brand new pirellis for their first magic lap during only their first heat cycle. Even still, I'm cheating using slicks & can't come close.

On this track the breaks do get very hot. The XR1 pads are spongy for me after just 5 minutes on track until they cool for a lap & then they are back to an aggressive bite.

One thing I have left to try, is to go back to the OEM carbon break setup to see if it helps buy me another second or two. I switched to the gyrodisk setup too early on to have recorded the time difference (if any).

I've yet to see any other road car do better than 1:28 there in person. He is just an incredible driver. I can't imagine what his lap times would be driving a 720s on slicks.

Just an FYI, Randy does do coaching...he's been out at COTA several times with some McLaren folks. A Day of his coaching, especially with him setting a data lap in your car, will be cheaper than all the other mods you are considering. And longer lasting.

 

[AWH]

With -3 degrees of camber in the front, -2 in the rear, 11mm novitec spacers in the front & 15mm spacers in the rear, on finspeed F10s 10x19 12x20 ET38 in front and ET25 in the rear before the spacers (I had a 20" F10s made for street use) w/ the hoosier R7s P295/30ZR19, P335/25ZR-20, ...

What is the interference point at the front causing the need for the 11mm spacer?

At the rear, I assume the interference is the brake duct?

 

[pepinozaur]

Hello Ian, just wondering if you had the chance to trying those tall slicks ?!

 

[ian.mcloughlin]

What is the interference point at the front causing the need for the 11mm spacer?

At the rear, I assume the interference is the brake duct?

Hey AWH, on the rear it was the break cooling duct & it was required to have the spacer to prevent rubbing.

In the front I actually have more wheel motion without the spacer. I was too worried about ruining the handling by changing the offset ratio from front to rear too much & I was worried about the damper hose.

 

[ian.mcloughlin]

Hello Ian, just wondering if you had the chance to trying those tall slicks ?!

I'll be at big willow test & tune Friday 2/12 to report back! Going to mount them tomorrow.

 

[ian.mcloughlin]

Quick Update:

Tires: 295/680/19 & 315/705/19 Pirelli DH
Wheels: On finspeed F10s 10x19 12x20 ET38 in front and ET25 in the rear with 11mm novitec spacers in the front & 15mm spacers in the rear

It was rubbing quite badly on the top left of the drivers side tire when I sat in the car with what I think is around -3 degrees front camber. We couldn't get the machine to give a reading, it kept failing when it rubbed. The tire is just too far out (I need to remove the spacers in the front so the tire is more inward).

Next Steps:

I'm trying the following before Friday of next week (planning another test & tune track day on the 19th).

1. Removing the 11mm Novitec spacers in the front & replacing the 15mm spacer in the rear with the 11mm spacer from the front. The front will have no spacer, and the rear will have an 11mm spacer. By my measurements it should still clear the break cooling duct just fine in the rear and the top liner. It looks like it will clear the damper hose in the front without any spacer. This wheel already has a nice offset. I didn't really ever need the front spacer, but added it to keep the front to rear offset ratio as close as possible. This should bring the front wheel in enough to hopefully stop rubbing on the top left.
2. Switching to the Novitec springs. I'm afraid the OEM springs seem to allow too much movement under compression. While the max height of the Novitec springs seems to be (<1") lower than OEM, I feel it will still be much higher under full compression/load. I got an amazing deal on novitec springs from someone local. This is what really led me to doing it. It should also help balance the car a bit (currently the front is way too tall vs the rear w/ these tires).
3. Going to then try get another alignment reading done after removing the spacer. The machine kept failing whenever the wheel would rub. I have an appointment to get the alignment reading and some time with the machine on Thursday (2/18).

I'll report back on the 19th. Open to any other ideas but the 295/680/19's might simply just be too wide (even after I remove the spacer they may stick out too much). However, they don't appear to be too tall (as long as you don't plan on turning the steering wheel > 180 degrees or it rubs on the door). That's perfectly fine for me, as these tires are track-only.

 

[ian.mcloughlin]

I didn't really mention it, but the rear was 100% perfect. I actually think we can go even wider & taller here than the 315/705/19 Pirelli DH. I just worry about the stagger ratio upsetting the TC with such tall ODs in the rear & not the front.

 

[pepinozaur]

Thanks for this great review, keep them coming!

First thing to pay attention: be 1000% careful when changing springs to Novitec, so the ECU has gone to sleep or the motion sensors from our suspension will fail for good. That really sucks, so please get the key out of the cars range and wait for 30minutes to be sure everything went to sleep.

As I see my car, I raised it to max height using the Novitec springs, and it might be less than 1" lower than OEM, it looks better too, I guess these are the springs used for 765LT too as Novitec uses KW to build their springs and.... KW uses Eibach factory to build theirs... if you have a look at OEM springs, they are Eibach Indeed the springs are stiffer so the suspension travel will ba a bit limited, that might be good or not in some cases as weight transfer will be limited too, from my only 2day experience with this setup I can say it felt pretty good, and my biggest enemies were the front and rear tires, as I felt wider tires are needed, both front and rear.... the car understeered and oversteered depending on situation... 235-305 R7s and AR1s on oem rims.

Now if you have custom ET rims, 38 and 25 if I remember right for front and respectively rear, there is no need to still run those spacers, I wouldnt at least... there is no problem either to use them if you rub somewhere, having those only for the the front might induce a bit of understeer, but having those huge front slicks, I think you will be fine

The 705 rear slicks are like 325 R888Rs (27.75") so they fit, but I dont think you can go bigger than that and Pirelli dont produce a taller slick afaik, the 705 pirelli slick is actually 707 and for instance the Michelin 710 rated slick is only 705 tall... so the rear is already BIG. We could try going wider later on using 325 instead of 315 if we feel the need to improve rear grip.

What I am really afraid is the front and using those huge tires 680 tall.... from the pictures, it doesnt seem the suspension travel is allowed to work properly before rubbing, I dont see how the weight trasfer would be possible when really needed.... hmmmm.... I hope those will work well, but imo those Senna slicks 285/650-19 besing 26 inches tall, might be a better fit for our cars, we just have to find a source to sell us those... Also having the front/rear OD ratio changed, that will give a lot more weight to the rear if keeping the springs at OEM rake, so maybe more rear grip and some understeer in the front that will offset the huge grip of this great front slick. Let's see...

I am looking forward to your tests and finger crossed to make them work, that would be my setup of choice too if you make it, please allow me to copy your setup

Congrats for your innovation and courage!

 

[AWH]

I'm trying the following before Friday of next week (planning another test & tune track day on the 19th).

1. Removing the 11mm Novitec spacers in the front & replacing the 15mm spacer in the rear with the 11mm spacer from the front. The front will have no spacer, and the rear will have an 11mm spacer. By my measurements it should still clear the break cooling duct just fine in the rear and the top liner. It looks like it will clear the damper hose in the front without any spacer. This wheel already has a nice offset. I didn't really ever need the front spacer, but added it to keep the front to rear offset ratio as close as possible. This should bring the front wheel in enough to hopefully stop rubbing on the top left

I still say just remove the rear brake ducts. 2020+ builds don't even have them (so I am told). One of mine is gone from a road hazard.

A lot of thought and testing went into those wheels' offsets and widths.

 

[ian.mcloughlin]

Thank you AWH for spending the time measuring & getting these wheel offsets/widths ironed out. They have been amazing so far.

pepinozaur, thank you for the help. I may just disconnect the battery to be safe! That would have been a disaster.

Just to be perfectly honest, I feel there is a very low chance these 295/680/19s will fit in the front even after the changes I'm making after work this week (removing front spacers & swapping springs).

We should all keep pushing to try & track down those 285/650-19TLP1-GTR SLICKMCs. If enough people are interested & we each commit to a few sets, I'm sure frisbyracetire.com or some other importer can help us track them down. That tire seems like it would be PERFECT. I'm really glad that you were able to track down the model #.

 

[pepinozaur]

Guys I am ordering the 285/315 Pirelli combo, I got a quote from a Pirelli Motorsport dealer here in Europe, waiting for expected delivery date and perhaps end of March/first week of April the finspeeds should be here too.

Will keep you updated on my progress, btw to have an idea of the costs of these tires, fronts are just like 50$ less than rears, I am still looking to see if I should buy the rears in DH, DHC or DHA (Ferrari GT3) compound

 

[pepinozaur]

Quick update: Tires were delivered today, as I am still waiting for my racing 19" rims, so all I was able to do was to try to have a home measurement of the slicks, as I had some doubts rearding pirelli own specs.

As you know the rear tire is huge and the front at only 650 height, might just upset the ABS and other supporting systems if enabled, but after using this tire ( R18 only) in my old 996TT, I was able to see that is more a 660 height and not quite 650. Also I have seen that 255-650-19 is also a 660 tall tire. So I assumed that the Senna GTR front tire will be 660 too and not quite 650.

My measurements are:
285-650-19 MC Pirelli Slick - 285mm wide and 660mm/26.0" tall
315-705-19 DH Pirelli Slick - 315to 317mm wide and 27.7" tall

I was hoping from both of them to be wider as the 18" version of 285 slick is almost 300mm, but no... This is actually good news imo as it reduces the risk to rub somewhere and still there is a lot of tire for our cars.
The rear was specced by pirelli to be like 328mm wide, but no.... 315mm or maybe maximum 317mm, other specs are exactly like in their papers. I have measured the tires unmounted on amy rim, not inflated. Just like they came from the factory.

My wheels should be here in about 2.5weeks, so I will come back here to report, but seems to me that I have discovered (with some risks and educated guess) perhaps the best slicks combo for our cars, in the end the fronts are MC rated. And one last thing, if the 315 rears are so narrow, I dont see a problem to use instead 325s in the rear. They should be MC rated too (also Senna/P1 GTR) and would try to use 12" wide wheels.

I was afraid that on one hand the 325 will rub, but on the other hand that the 12" wide rims will be to narrow for 325s. Maybe not..

Really happy now and waiting for those rims, I am considering for these slicks running at least -3.5F/-3R camber and leave caster and toe as they are now.

 

[Middachten]

I’ve been reading this with some keen interest. Having learned to use the massive increase in cornering grip with slicks on other cars over the past year, I have started wondering what it would do for my 720s....

I have some experience now with the difference between the Corsa and the Trofeo. But still find it challenging to cope with the front behaviour compared to driving my 570GT4 on slicks. And I would want to have a slightly softer compound than the Trofeo has because 50% of the time temperatures here are too low to get some decent heat in these tires...

But I was wondering: what will the increase cornering loads do to the bearings/bushes/struts of the 720s?
Have you noticed any additional wear due to this?

 

[pepinozaur]

I have no idea regarding the wear on the long run, for now everything looks good but only tried hoosiers and nankangs.
Maybe somebody who ran on slicks can chime in..

I supose we will have to change bearings and bushes more often than in the maintenance plan, really no info regarding the struts, but I would love also to switch to Senna accumulators too when possible. I dont know the specs for senna gtr suspension, if still hydraulic or not.

If the Senna GTR still runs on hydraulic suspension then maybe we are quite safe... will dig more into this.

This weekend I have set the new road car track record for our local track on 235/305 Hoosiers R7, the time is in the ballpark of TCR cars, 991.1 cup or 458 challenge on slicks. Next week I will test 265/305 Nankangs and hope to match that time or be within a second of my best on hoosiers.

I will move from -2.2 on all four corners to -3 & -2.5 and from toe out in the front to very little toe in. The rest should stay the same. Will post here my next results, still trying various allignment and tire setups.