spiller

Thanks for the input, I probably can't get 305s here in Australia as they're hard to get. With the 315s, did you find running the higher pressures to compensate sacrificed grip at all?

powdrhound

No, not really. Even at higher pressures the short 315s just felt overwhelmed by the rear heavy car. They lacked the grip and the solid feel of the 305s. I think it has to do with the fact that the 305s carry a higher load rating and have a greater contact patch. On my car it also helped that the 305s gave me slightly taller gearing which helped but the change is very subtle...

Not sure what alignment you have but I run -3.5 front and -2.5 rear camber. Wear is dead even across the tire and basically 1-1 front to rear.

PAULUNM

Somewhat unrelated question- do you all notice your NT01s flat spotting if you leave the car parked for 5+ days?

Doesn't seem to be permanent, but lots of shaking at highway speeds for a few miles, then back to normal.

Wondering if I need some anti flat spot parking pads...

4porsh

I notice this, it goes away. All good.

hf1

Been running 315/245 NT01's for couple of years. 35 hot all around. 30 is way too low. This means starting with 24 (or lower depending on temps) which could damage the sidewalls from too much flex before the tire gets to 30.

Regardless of how slippery the tire gets you need to adjust your driving and learn how to catch it before it spins. It's probably not the tires, it's your butt dyno that needs work.

spiller

I somewhat agree with your point there but I cant get my head around accepting that a tire will be slippery and "getting used to it". They're there to keep you on the black stuff at the end of the day. As I said in my OP...at the low pressures the grip levels were great, especially off the slow corners, it was just a confidence thing. Plus im not about to go encouraging slides at 140 mph - already done that once in this car, needless to say I did not catch it and don't want to do that again!

hf1

I didn't suggest that you get used to it -- just adjust to it during the short periods when it happens unplanned, like in the rare cases when tires go 40+ due to hotter than expected track, more aggressive driving, or during longer sessions. And I wasn't encouraging 140mph slides. Hopefully your butt dyno would have caught the drop in grip way before committing to take a high speed turn at 10/10s assuming the usual grip was there. Tire grip changes constantly during a DE session or a race for all sorts of reasons. Your butt should be listening at all times.

For me, nt01s behave best (incl max grip) in the 34-35 area hot. Higher than that, grip drops off quickly. Lower than that, I haven't noticed much increased grip, if at all. Even if there was a small grip gain in the 30-32 hot area, the risk of damaging the sidewalls when starting in low 20s cold would not be worth it to me.

CosmosMpower

Ran a set of the 245/305 NT01's and not a fan. When full tread they squirm a lot, even worse than top tier street tires. When the tread is gone they aren't any grippier just less squirmy. I'd run Bstone RE71 or go to something like a Hoosier/Pirelli DH and skip these.

At COTA I was 4 seconds a lap faster on Pirelli DH than NT01.

spiller

All good, thanks for the tips with regards to pressures. Could also be that given my car is a fair bit stiffer than a stock GT3 that it perhaps doesn't like the higher pressures. That and the track I run at has multiple slow corners with high acceleration zones - would be it be correct to say lower pressures would be more favourable in this environment? Talk of side wall damage, is this a known issue with the nittos? I have start them around 25-26 cold on the 6 sessions I've done with them thus far. Will start them a bit higher next time to experiment with the higher hot pressures but curious about the sidewall issue you mentioned. Tire pressures are a bit of a black art it seems, lots of guys at the track have their own tricks but dont necessarily go into details with the reasoning behind their methods!

spiller

I will try the nittos another couple of times but once I get some track wheels they will become my street tyres. I'll probably go with Advan A050 for the track in future - very quick tire but I don't believe you can get them in states for some odd reason.

tgavem

I am 3 years with this hobby and never tracked before. I started with AD08, then AD08R, R888, and now NT01.
AD08 - fantastic tire with very stiff sidewall but greasy above 90F, 34/35F- 35/36R
R888- better than the AD08, did not last through 3 weekends
NT01 - softer sidewall, squirmy under car first 4 -25min sessions to remove top layer. NT01 took me 2 days to get used too. I run 600/800 spring stiffness. I found 33F-34/35R is a good pressure. Start around 27 all around cold. Gentle throttle first 1.5 laps to get tire pressure up. Best grip is through first 6 laps, then start sliding but nothing alarming. I can control the rear with confidence and get the slip angle just right or even if I go over, small throttle adjustment (and steering) will get the rear back in.

I do have a Guards 60/40 LSD. Have you upgraded your LSD?

I have seen about 1 sec improvement from the R888 to NT01. Not a big gain but NT01 last a little longer and don't heat cycle out like the R888.

hf1

My springs are 600/800lbs (per inch compression). Can't answer if stiffer springs like lower pressures. (I would think the opposite -- stiffer springs would need stiffer/stronger/less deforming sidewalls -- but no expert here.)

Nothing specific about nittos. No tire wants to be squirmed left/right accel/brake on low pressure. Just pure physics -- lot of deformation going on. That's why people who know anything about tires don't warm up cold tires by darting left/right behind the pace car -- that's "amateur hour" . This weakens the structural integrity of the sidewalls and may make them more prone to failure later. Tires should be warmed up by gentle accel, braking (the heat from the rotors spreads to the wheels/tires) and taking a lap or two without too much latteral g-forces in turns. The less jiggle on the sidewalls (which are maximally deforming from the weight of the car) under low pressures, the better.

powdrhound

I start at 25/25 cold on them and shoot for 32/33 hot on the 245/40 and 305/35s. Once they get close to 35, they get greasy. I'm on 1400/1500 springs... No sidewall deformation whatsoever..

spiller

Thought I would update as I went back to the track yesterday. 90 degrees ambient all day and I started cold at 26 front/25 rear. Set my best times with the hot pressures at 32/33 as per many recommendations in this thread. Squirmy feeling gone. Only complaint is the pressures would not stablize at any point throughout the day (despite ambient temp being the same) and continuously over inflated by lap 4 out of 5 in each session. This was despite bleeding 1-1.5 psi each time. Slides were controllable and fun however!