adrianko43

iTrader: (2)

Is anyone here running on NT-01s and what size? I think that the only options for our cars are to run 245/40Front 275/40Rear, or
275/40Front 315/30Rear.

My concern with 245 fronts is that i be getting too much understeer. And since my Z is n/a, would 315 rears be overkill?

Please let me know what you guys think. Thanks.

Edit: I'm going to be using 18 x 9.5 rims all around.

GaryM05

On the OEM 17" wheels, I'm running 225/45 front, 245/45 rear with the NT-01s.

On your setup, 245/40 front and 275/40 rear would be the way that I would lean. Depending on your mods, you might be able to dial out any resulting understeer (but you might not notice much, as I run those sizes on my street Volks, and don't notice much understeer at all).

Another option to consider, if you're that worred about understeer, would be running 275 all around. There are others doing that, who have managed to fit 275's up front, and have been very happy with this setup at the track.

pedroosan

iTrader: (1)

when going for 275 in the front I think the better size would be 275/35/18
and the nt01 comes in that size according to nittotire.com

If you go 275 all around, and don't want to keep the stagger (275/35 front 275/40 rear) to be able to rotate, then I believe you can do 275/35 all around.
At least I think the toyo RA1 don't come in 275/40 and as far as I have researched here most people run RA1 in 275/35 in the rear.

smaller diameter in the rear can be beneficial at the track (better gearing I think)

But keep in mind that VDC should probably be off when you don't stagger.

I could also imagine that you will fit the 275/35 in the front better than the 275/40

Experts out there correct me if I am wrong... don't want to spread bad info.

Eagle1

iTrader: (2)

I agree with Pedroosan. On those rims run the 275/35 all around and it ought to be great. You will want to be driving without the vdc on a track for sure, but if you are having any doubts about that at all......leave it on. You cannot run the 315/30 nitto without using a 10.5 inch rim, and there are very few good rims in that width for 18" diameter wheels. (I am using the Enkei NT03+M and running 275/35F and 315/30R). The 315 is actually about 323mm treadwidth, so be careful...it is a lot to stuff in there and depending on your shocks you may have some rub unless you put a 3 to 5 mm spacer, and then that could require a little bit of fend rolling with the old baseball bat to keep from rubbing.


Here is a picture of that set up going through Riverside at Buttonwillow, #13 CW

adrianko43

iTrader: (2)

Thanks for the quick replies. Although nitto advertises 275/40/18, i have not been able to find them online, so I'll go with the 275/35/18 all around, and I can dial out any under/oversteer with my coilovers.

One more question: On toyo's website, they say that you should run their tires with at least -2.5 camber or you will experience irregular tire wear. Is this also the case for the nittos? I dont have adjustable A-arms, and my camber is currently set at -1.5

Riverside scares me, the rear of the car always feels so light, and unweighted going through there. But that was before got my coilovers.

350zippy

i have 245/40-18 (f) and 275/35-18(r) on OEM track wheels.
have you guys fitted a 275/35-18 on front OEM track wheels without problems? tia.
regards

Eagle1

iTrader: (2)

Yes, you should put in 2.5 to 3.5 negative camber in the front. I have been running that camber on the Nittos and had very even wear with track use at Buttonwillow, Sears Point and Laguna Seca on the same set. Very excellent experience with them so far.

The coilovers will help a lot. Did you lower the car all around in the process?

The Nitto is going to give you a bit more dry grip and sidewall modulus than the RA-1. (Bigger treadblocks and stiffer spring back sidewall). It is also a bit noisier. (wide siping in the tread). In the wet....don't use it.

Riverside should be respected at all times. High speed, on the edge adhesion turn that has no happy outcome if you lose it. Either direction presents roll over risk if you drift off the outside. Unless you have significant experience in recovering from loss of grip at high speed with countersteer inputs, and very few do, you could find yourself in a position where the tire stops talking to you and lets go in a slide, and you have nanoseconds to put in your counter steer to get grip back. The back of this car is heavy, and you will drift out and take away your safety margin quickly. Too much input and you snap it all the way around the other way. There are places to push the limits where the consequences of such a mistake are not too great, and others that are grave. So use your head. On CCW, stay high and out left on entry and remember that the end of that turn pinches down in a diminishing radius, so keep that turn in to the apex very late. Your speed when you pinch that apex, and you then at that point are back on throttle hard, just right will drift you all the way out to track edge left. Being on throttle helps sit the back end down....but if you lift it puts weight forward, and LIGHTENS the back even more just when you cannot afford that. So "squeeze" on the power smoothly and work up to WOT....don't mash it down in a stomp, and work your way up to your best exit speed safely and comfortably. This is not as late an apex as turn 9 at Big Willow, but certainly similar to that. On CW, especially if you are not using DogLeg but instead are taking the cut down through Bus Stop, you really must stay high (now to the right, obviously) so you can get the widest arc through the turn and carry speed, as well as set up a good straight braking line before taking that "thread the needle" turn to the right across the rumble strip curbs, first right and then left side. I don't think it is quite as hairy as CCW direction, but there is for many drivers a tendency to not be quite as challenged by a right to left versus left to right turn, even the same one.

It is pretty cold now in the mornings in the desert, and in the Valley at Buttonwillow. The morning runs are going to have that asphalt sucking the heat out of your tires. It will take at least two laps to warm them up, and frankly, I would not try to be pushing your limits in any of the morning sessions that you run. With any luck at all the day will be bright and sunny and you will get air temps of around 65-70 degrees by 1:30-3:30, and then you can get a bit more frisky.

Beau

iTrader: (4)

^^^Forget about saving for modifications, I just want to save money for track days!!! I almost felt like I was getting briefed before climbing into my car at the race track.

WA2GOOD

iTrader: (24)

Hahaha... Yep!, Ed (Eagle1) does have a way with words, especially when writing about track experiences. He put his experiences into words better than anyone I know.

I always love reading your peotic way of words in your posts, Ed. See ya soon. (Redline Time Attack 2/10-11/07)

Eagle1

iTrader: (2)

Thanks Beau and Scott. Most appreciated. Just trying to give the most useful, and not misleading help. We all learn differently. Some folks can just jump in a car, any car, and drive like a rocket. But ask then to describe, EXACTLY, what they are doing and why, and it is a hard challenge for them....they are not wired that way. But get in the passenger seat and ride with them and they can SHOW you. Scott drives like that. He knows his stuff and is WAY FAST. He just started learning when he was a munchkin in go karts, and it is a second nature or instinctive thing with him.

I come to game late in life and after many other types of sporting and "muscle and reflex training" experiences. I knew I was a really good and safe driver on the streets and that this would just be an extension of that. Oops, imagine the shock when after about 90 seconds I began to realize how wrong that impression was....how dumb I felt! So, learning for me had to be analytic and reflective, a slow and deliberate process. Partly because I am not of the mind to learn for the first time by experience without preparation. Taking the Roval at 135mph at Cal Speedway was one of those situations that also taught the limits of analysis WITHOUT experience. Man I studied that sucker. Watched film from other drivers, read up on posts, got the line and turn in and everything down. Guys were doing 150mph in there and I figured, I will do everything just like them. Got up to about 155-160 going down that humungous front straight, eased off throttle and let the wind resistance bring the car down to a stable, settled 135mph, got the turn in perfect, held throttle and dived into the turn right on the target line...........
and basically had my anus pucker to the diameter of a BB. Did not breathe, burp, fart.....I was scared spitless. WHY? Everything was as planned, right?
Everything but the actual experience of pulling that kind of speed and realizing that IF something went awry I might not have the recovery skills to safely navigate out of it....and hitting a concrete wall on a banked NASCAR turn at that speed was never so real. Got my fanny into a racing school so fast after that. Now, not bad at all. So the writing is a way to create a learning experience that us mere mortals, regular talent (or perhaps in my case even less than regular) guys can visualize and understand what is going on. It may be redundant or useless for some folks. But for some of us, and certainly for me, this type of presentation brings to the mind a way of grasping and understanding what is going on, so that then it is easier to take the next learning step of what to do and why. I need to know WHY the car is doing something and HOW, to develop my instinctual reactions. Do it "because" does not work for me. Do it because you are understeering....that does not work for me. I will never be able to drive like Scott. But that is just the way it is going to be. Just have to settle for being able to describe how it works for me, and hopefully enough others will have the same response to make it seem relevant and helpful to them.

Eagle1

iTrader: (2)

Here is a picture of the car going into Turn 5 at Laguna Seca, trail braking and getting some rotation of the rear (note the lift on the inside rear tire, a NT-01 315/30/18, and the forward compression on the outside right tire that is taking the major load for turn in, a 275/35/18).



In the second picture you can see there is still a fair amount of steering dialed in as we hit the apex point (in fact we are off by a couple of inches too far outside the target point), and the weight is beginning to transfer back to the rear as we are squeezing back on throttle just before apex.



In the third picture the steering is unwinding and the rear is settling down even more as the weight transfer to the rear progresses under acceleration and we move to the right side of the surface under track out.

adrianko43

iTrader: (2)

Nice picture and descriptions.

dorikin_86

iTrader: (2)

you guys can always call discount tire direct to place an order for sizes you see on nittotire.com.

online tire retailers doesn't stock all sizes that's why they don't always list them all. I bought some street tires for my daily car and I had to tell them to special order it in (255/35ZR18 invo). No tax and free shipping (for CA guys) is worth it for me to call =)

Eagle1

iTrader: (2)

You can also just call up the local store. I bought several sets of tires through the Colorado Blvd, store in Pasadena, Ca., with America's Tire (a Discount Tire store), and they were outstanding in service and price. They also can speed balance the tire for higher track speed on the machines they have at that store. They did such a good job for me at that particular location, that I bought some Enkei wheels for my wife's car there, and some heavy duty truck tires for my tow vehicle.