Nitto NT555 Tires + Track = no good.

[naikaidriver]

I have two track days on my NT555s and I didn't experience anything like that.

The first time out I went with 32 psi all the way around and the car felt very loose. The second I went with 28-29 psi and the car felt perfect with the tires coming up to about 36 psi at temp. Outside temps were around 89 degrees that day and track temps were around 94.

TRMP here is all smooth asphalt also.

Do you have track video? Telemetry? Without any data, I feel like we're all speculating at best about the possible cause.

Scott

[frenchsquared]

You need to get something to measure the tire temps. I don't go off air pressure. When I got my first set of R7's I called Hoosier and ask about air pressure. They gave me a few starting points but explain it was about temps. If the tire is to hot it will break down. Now I pull in have a friend check my temps and then go back out to cool the car down.

[Nor Cal ZL1]

Originally Posted by frenchsquared

You need to get something to measure the tire temps. I don't go off air pressure. When I got my first set of R7's I called Hoosier and ask about air pressure. They gave me a few starting points but explain it was about temps. If the tire is to hot it will break down. Now I pull in have a friend check my temps and then go back out to cool the car down.

Thats the way to do it. Air pressure is to set mid tire temp only. Proper camber and gain curves the tire should read about 10 to 15 degree spread. Inner warmest, middle 5 degrees cooler than the inner, outer 5 degrees cooler than the middle. If you can't achieve these numbers your camber is off, or you are overdriving the tires. A pryometer is cheaper than going through tires due to suspension/alignment issues.

Seen many ruin 1500+ sets of tires and refuse to dial in the car using tire temps. AnytIme I'm asked about tire pressures I ask for temp info. It is also possibe to have the numbers correct and just overdrive the tires. Adding pressure such as what you would do for a high speed run like the texas mile does not work in lowering temp on the road course. Having a full proper contact patch is the only chance. At a minimum the tire should at least be even across. Check the tires off of a hot lap, with 0 cool down.

[stratman2SSRS]

Reading this thread is very interesting.
So what temperature is the target you would be looking for?
Does the air or track temperature affect it?
And does it varry between brand or model of tires?
I've recently purchased som R888's and will be tracking them next season, and don't want to wreck them by abusing them by not watching the tire pressure/temp.

[Norm Peterson]

Originally Posted by stratman2SSRS

Does the air or track temperature affect it?

Air and track temperatures will affect the temperatures that tires will reach, but I have no idea by how much. As far as I know the optimum tire temperature/temperature profile across the tread remains the same.

More important on cool days is that tires take longer to warm up, compounded by not being able to 'push' them as hard as soon. If the 'out' lap is good enough at 70°F, plan on two or maybe even three laps of gradually increasing intensity if temperatures are down in the low 40°'s. I've been to events where temperatures were as low as 40° for the first run group of the day.


Norm

[Nor Cal ZL1]

Originally Posted by stratman2SSRS

Reading this thread is very interesting.
So what temperature is the target you would be looking for?
Does the air or track temperature affect it?
And does it varry between brand or model of tires?
I've recently purchased som R888's and will be tracking them next season, and don't want to wreck them by abusing them by not watching the tire pressure/temp.

First the optimum tire temperature must a known. That can vary quite a bit between manufacturers. The ambient temps will affect how quickly they will come up to temp.

Once the optimum temp known you can diagnose, however the temp spread can be done as long as the tire has a reasonable amount of heat. In a flat out racing situation the overall temps are viewed to look at front to rear as well as cross balancing.

In a trackday situation where a car has no spares, or much in the way of trackside adjustments, your going to come in off of a hot lap with 0 cool down. Immediately measure across the tires starting from the most loaded front Ie majority of turn direction and mesure across with a probe pyrometer, quickly record the info, and move to the next tire.

The tire pressure is to set mid temp ONLY. A typical good set up will have a spread of about 10 degrees hottest at the inner growing cooler towards the outer. The middle should be between these measurements. If it is too high remove some pressure, if it is too low add some pressure, usually in 1 psi increments, unless it is way off.

So for a quick example or two we will take a look at a few possibilities using the drivers front.

Outer/155 Middle/150 Inner 145. Bad alignment not enough negative cambe. Inner should be the hotest. Car needs alignment and more negative camber.

Outer/155 Middle/160 Inner/165. Spot on good camber, proper pressure.

Outer/155 Middle/165 Inner / 165. Too much tire pressure

Outer/130 Middle/150 Inner /170. Car has an excessive amount of negative camber and needs to be corrected.

Outer/155 Middle/130 Inner 165. Under inflated add preseure. This is a significant amount. Add several psi and re test to check results.

Most likely though your numbers will be closer than some of those examples, but checking the readings will show you what direction to take.