Martin S.

My 2004 GT3 is a street car that I take to the track now and then (6X per year is the plan). The only mods are safety related, welding the coolant pipes., etc. I have a second set of wheels and do want to run track focused tires, Nittos are my first choice based on price and durability, 30% cheaper than Hoosier R7 tires, and at least 2X the # of heat cycles. In searching and reading the GT2/GT3 Board vis-a-vis DOT 100 tires, Nittos seem too get high marks, BUT, I am concerned with their fitment.

I have this brand new set of Nitto NT-01 tires, 245 for the front and 315 for the rear. The fronts should fit OK..I have 245 R7s in there now. On the rear, I have 295/30/18 R7s in there, looks to be a tight fit. No rubbing, after all it is the stock size...but is there room for a tire that is 20mm wider without dialing in more rear negative camber? Or, perhaps raising the ride height?

I will have the car on the alignment rack this week and will measure ride height and check the alignment specs. At that time I will do a trial fit of the 315 tires. The 305 rears are 10mm narrower than the 315s, but they are nearly an inch taller, thus changing the final drive ratio and potentially rubbing the fender liners.

Based on my experience with my former 993, a track alignment will address some fit problems....but cars with a track alignment can eat up street tires: I don't want that. So what I am wondering, are people running the 315 tires with stock alignment without rubbing issues? Let's assume that is not the case...then the question becomes, what are the alignment specs required to successfully run Nitto NT-01 tires, front and rear, assuming 245/40 on front and 315/30 on the rear?

Thanks in advance for any responses.

Martin S.

Let me answer my own post (Go ahead Martin, it's OK)....I have made a "course" change and will NOT be going to the Nitto NT-01 245/40/18 fronts and 315/30/18 rears. I had them mounted up, but will dismount them in a few weeks and put them up for sale. They have 0 miles. I'll price them competitively.

In going to the stock GT3 tires sizes of 235/40/18 front and 295/30/18 rear, the Michelin Pilot Sport Cup 2 seems to be the only source for this exact size. Hoosier R7, Pierlli's P Zero Corsa and Trofeo R*** make the 295/30/18 rears, but their fronts are all 245mm wide...which is OK, I have 245mm Hoosiers on the car now and they fit. I also have a set of Pilot Sport Cup 2s in the garage, so that question is solved. New they appear to be about $1,500 a set delivered.

I also really like the Hoosiers R7 tires...I saw a set to under $1,300 delivered to CA. Not quite as versatile as the Michelin Pilot Sport Cup 2, but one hell of a tire, running them now.

***Tire Rack has a video with Randy Pobst driving a new Camaro shod with the Trofeo R. He was very pleased with their performance. The review on the page were very positive too. Not so much with the P Zero Corsa.

If I stick with the stock 235 and 295 sizes, I don't have to worry about tire rubbing, etc. And personally, I just don't see how a 315/30/18 NT-01 can fit into the rear wheel well...people say it does, but I personally don't see an incremental 20mm there to stuff these monsters in. As for the 305s, too tall. My GT3 stock gears are long enough.

Thanks for your contribution Martin, and thanks to Rennlist for the confessional! I needed it.

AudiOn19s

if they are mounted and sitting there why not take the 10 min to put them on the car and take if to for a drive to see if they rub. Nitto's don't require a TON of camber to work for track use...-2.3 is about ideal for them which isn't that far off from stock specs which means those of us using them don't really have radical alignments to make them fit in there.

I'm a little hung up on the stock alignment thing still anyhow. I mean the car is setup for the track and you are obviously tracking it...you're either going to kill street tires or track tires depending on where you go with alignment, I'd personally rather kill street tires than track tires. You're also giving up soo much front foot print with not only the smaller front but the lack of camber to put that front footprint to to work for you at the track.

I drove around on the street at -3.0 front camber for 4 years on a set of pilot sport 2 tires and never killed them, the rears wore out first. It's only going to take a couple of track days at decent pace to cord a set of tires at the track on the wrong alignment.

onelove

I'm with Andy, if you're going to take the time to set the car up for the track, shifting the alignment shouldn't be a huge issue. Camber often gets blamed for horrible tire wear on the street, when reality Toe is often the culprit. If you keep the tow in check on the street you can run more more aggressive camber than the factory and get the most out of the tires. The track presents the opposite scenario, far to often I have seen customers and friends spend big $$$$ on a set of tires, only to have them wear one edge prematurely from not having a proper alignment (more common with Boxsters / Caymans, etc where the oem control arms don't allow the alignment freedom that our GTs do from the factory).

I've run the 245/315 NT01 setup on my car at the track, ti's a great setup with a proper alignment that will allow for quick lap times without breaking the bank. Sure I can go quicker on a Trofeo R but the incremental expense for me at the DE level doesn't warrant the price of entry over a marginally slower NT01 at a fraction of the cost.

Martin S.

Wes and Andy,

Great advice...I may have been in a bit off a funk when I responded to my own post. I will try the 315 Nittos on the car...I know the 245s will fit, well at least the Hoosier R7 tires fit.

Wes mentioned, "it's a great setup with a proper alignment that will allow for quick lap times without breaking the bank." Could you be kind enough to provide me your alignment recommendations?
That would be appreciated.

Bottom line, I spent a hunk of change prepping the car for the track to include, welding those pesky cooling pipes, buying and installing a RSS 931 roll bar****, a Recaro Profi XL seat with Recaro sliders and side mounts, Schroth 5/6 point belts, fire extinguisher, a thorough covering in XPEL and changed the rotors from PCCB to iron, with GIRO 2 piece on front and 997 Turbo on the rear and a second set of GT3 wheels. So I had better optimize the track experience with the best possible tires...there, there now, I do feel better, thanks again for talking me off the ledge.

****. I can report that there is 0 and I truly mean 0 interference with rearward seat travel on the Recaro Profi XL and the stock passenger seat using this roll bar. Yes it's a roll bar, a step up from a harness bar such as the Tequipment bar. The RSS attaches to the shock mounts in the rear, and bolts the hoop to the chassis....3 holes needed to be drilled on both sides of the car, just aft of the "B" pillar, and the appropriated heavy duty bolts inserted. The Cantrell roll bar is a very similar design, up forward it bolts the hoop to the chassis.

himself

As noted in your other thread, almost everyone starts with Kussmaul and modifies it. You can search for "Kussmaul" on Rennlist and get a bunch of great alignment suggestions.

For non-stock suspension/setup, IMO, the best tires for the track are Pirelli DH. They have a great sidewall and last a long time. I can get almost 2 full weekends out a set (about 16 sessions). The last few sessions aren't stellar, but doable. For stock setups, the Nittos [and virtually every other R-comp tire] are a good choice. And, R-comps are a good learning tire as they have a very forgiving grip profile. With the stock setup, the car sets slower, which is great for the Nittos. [This is another reason NOT to mess with your ride height] Interestingly, my data shows that Nittos have almost the same maximum grip loading as the Pirelli's, but it takes longer to get there in a corner or braking zone. So, this is where most of the time is lost when comparing tires. Alignment is almost the same for the two tires. I run a little less negative camber for the Nitto's in the rear, and that's about it.

-td

onelove

I started with the Kussmaul and got rid of a touch of toe in the rear to help with the street-ability ( I also run a full RSS Tarmac kit on the car with their control arms front and rear, all Spherical bearings, etc). I've put probably 30-40k miles on this setup and a number of track days with no issues or poor tire wear.

A quick check at the track with a pyrometer can give you an idea if you're that far off base with the alignment on your specific tire (take inner edge, outer, and center right when you get off track as well as pressure and keep a log of this as you go).

spiller

Are you referring to the Pirelli racing slick? How much distance are you covering in 16 sessions? Are the wearing out of heat cycling out? I hear they tend to cycle out before they wear out...

himself

Correct, the Pirelli DH slick. The DH is the endurance compound. They have a great set for our cars 315/645 and 245/645.

If you have a good setup and right tire pressure, these tires seem to cycle out and not wear out. But, even when cycled out, they are still as fast as NT-01s. You can run them all the way to the cords and still be pretty fast. [I've never tracked distance, so I have no idea how far they go. If I had to guess, 25 minute sessions @ 3 mile track with under 2 minute lap time, is around ~10 hot laps, or 30 miles. X16 sessions = around 500 miles. ~500 miles sounds reasonable].

-td

spiller

Thanks for the info. 500 odd miles from a racing slick is very reasonable! I have purchased a 996 cup and this is the tyre that everyone recommends over here in Aus.

Matt Lane

I know you have decided to go a different route Martin, but as others have confirmed here and the other times this question has been asked, yes the 315 fits perfectly on a car with +/- Kussmaul height and alignment settings (which are not extreme by any measure). The main issue you'd possibly have would be the front, keeping Caster in check (I needed caster pucks to bring the front wheel back a bit, was rubbing the plastic fender liner). Do a search, lots of good ideas here on how to get a compromise setting that works, doesn't kill tires in dual use, not too low to run on the street, etc.

I ended wanting a bit more front camber than Kussmaul, which I dialed into my last alignment. I feel I now have an alignment well-suited to the stick of the NT-01, my (modest) driving ability, and driving on the street where I run cheap tires to offset the cost of some sub-optimal wear...

Cheers

Matt

cgfen

.

I know there is a lot of discussion about 305 / 315 rear choice.
i'm more interested in front tyre choice.
I'm concerned that 245 - 40 fronts will rub when wheel is turned more than 30 degrees or so.
I had a set of 245 X 40 AD08Rs that rubbed and I had to go back to 235 - 40.
Front camber is ~ -2.6 degrees
Not sure about caster, but my alignment guy seems to know what he is doing and sets up a lot of local race cars.
Car is low, not sure of actual ride height, but see photo.

Does anyone have a 245 - 40 NT01 laying around they could measure the tread and section width?
I could then compare to my AD08.

Thanks
Craig

powdrhound

I run the Pirelli DH in a 275/645 and 315/680. They will cycle out before they wear out. I get about the same life out of them as the 275/335 NT01s I ran prior, roughly 10-12 sessions of 25-30miles each... The DH are great tires with the downside being they are about 2x as expensive than the NT01s. With that said, I would never go back to NT01s. There is simply no comparison.

Nickshu

Craig I have a brand new "sticker" set of NT-01 fronts sitting in my garage right now, unmounted. I can measure them tonight if you want, but the numbers are on Nitto's website.

https://www.nittotire.com/competitio...d-course-tire/

blotto649

Re. the 645 front and 680 rear, does anyone know if this difference in circumference is okay to run on a car with stock ABS? I don't have any supporting evidence, but I ran 645's front and 660's rear for a short time a few years ago and noticed some weird brake pedal/ABS behaviour, wondering if it's related. I normally stick to 645 front and rear.