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THE TIRE THREAD : tires info

flyhalf

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Hey guys,
first of all, happy new year
I thought we could start to share info on tires, in only one location. There are tons of spread advice around the web and this forum. Let’s put our knowledge here!
I'll start sharing my experience with 7 different compounds in the last 18months.
now, I'm not an expert road racer. (I just did my first year at the American Muscle Cup time trials).
but maybe this can help to navigate many rookies like me for the best tire choice.

My experience is on HPDE and time trials only (no w2w ...yet :D)

As mentioned,

I tried 7 different tires. Some more consistent, some just recently tried so my evaluation is still partial.
ONE THING FOR SURE. Mustang 2018 LOVES TIRES AT 34PSI AS PERFECT PRESSURE

list

  1. MICHELIN 4S (OEM MUSTANG PP1 255F 275 R)
  2. NITTO NT01 (305 SQUARED)
  3. RE71 (285 SQUARED)
  4. 3R GOODYEAR (305 SQUARED)
  5. CUP2 (305 SQUARED)
  6. YOKO A052 (295 SQUARED ON 18')
  7. KUHMO ACR (295/25)
IMPRESSION

1. 4S.

a. 500miles on the car and ‘Laguna Seca happened. I ran stock 1.44 and those tires, gave a good feedback and performance actually. They wear well and probably top street tire for daily use. (with some sporadic track day). A great tire to start tracking the car.
4s 275.PNG

2. NITTO NT01

a. highly suggested my many people, I think is a great tire to start to learn how to drive on the track. Very predictable and limit never comes in one shot but it is gradual. So, it allows you some mistakes. Great wearing especially if tires are rotated all around often (I sold mine with 8 track days and at least 4 to go). For sure not the fastest. Awful street tire. Awful rain tire. and the heavier ( up to 5 lbs heavier )
nt01.PNG

3. RE71.

a. My Muscle cup tire (size limited by class) .one of the ‘princesses’ for time trials. I usually used them with 1 hot lap 1 cool off lap format (also because my overheating problems lol). DEFINETELY ONE OF THE FASTEST. 285 is small for a 4000lbs car. wearing was ok. Although with stiffer sway bar I started to see some bigger wearing (maybe due to the drag that the sway bar induced.). I would say, 4-6 track days is the normal life of those tires. I HAVE NO EXPERIENCE WITH them on 20mins session with hard pace. However, it happened many times to do my best lap at lap 5 or 6. One of the top choices here.

4. 3R GODYEAR

a. I think those are my favorite. and probably top3 fastest (if not the fastest…). great feedback. They are very precise especially in corner entry. also, because the largest thread width.5/32 depth for the thread. Don’t expect more than 3-4 track days with rotation
3R DATA.PNG

5. CUP2..tried only one session…I don’t know I think they are over all slightly slower than 3R. better and precise on braking zone. Worse in max G turning. In Sonoma they were pacing slightly slower than session before with 3R (around 70f outside). I’ll test them again.
CUP2.PNG

6. YOKO A052. 3 SESSION IN BUTTONWILLOW one with rain. The third one was pacing 1 sec faster than my PB with 3R (although 3R PB was with 90f ish while it was colder this time). I ruined the lap finishing out. So far great wearing! And fast tire. I have the 35 so maybe little softer than the 295/30. I will use them for my JAN/FEB testing. Results seems encouraging between the lap time and the wearing.
20191230_113138.jpg 20191230_113154.jpg 20191230_113144.jpg YOKO A052.PNG

7. KUHMO. Side wall…25..small very small. But I was expecting a lighter tire (27lbs..probably cause the carcass is very reinforced. The don’t like camber. So, I did change it before installing them knowing the toe will be off. Like 2 laps only thing. So, I put them only one session on the fourth one in Buttonwillow. I did. 1.2 sec faster than 3R (but 3R with 90f). I Did my best at the first lap and second lap; TIMING was way slower DUE TO HIG PRESSURES reached in the front where I change the camber. (rear was perfect at 34psi rear went to 38psi)
KUHMO ACR 295.PNG


I'll update it once I have more info but PLEASE SHARE YOUR INPUTS TOO, INCLUDING DOT TIRES AND SLICKS. with time comparison if you have it too.

Happy new year,
Alessandro

RE71.PNG
 

flyhalf

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295/35/19
3 trackdays
11 sessions

Also 1 in the rain.
Great grip. Consistent through the day and during the session

Those tires surprise me :)

Sharing ome example of 3 laps very close eachother. Also session after they were 2 tents faster.

20200210_094458.jpg


20200210_093929.jpg


20200210_094458.jpg


20200210_093929.jpg


Screenshot_20200210-154238.png
 

bob

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ONE THING FOR SURE. Mustang 2018 LOVES TIRES AT 34PSI AS PERFECT PRESSURE
Alex,

Did you come to this 34psi hot number by tire pyrometer or fastest laptime?

Interestingly by chance I came across the same 34psi hot target on the OEM 4S just picking a number then going up or down by 2psi increments over about 4 total sessions 1st raceday. Unfortunately in my race I thought dropping out another 2psi would be faster but it was noticeably slower. 34psi worked on the 4S.
 

flyhalf

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Alex,

Did you come to this 34psi hot number by tire pyrometer or fastest laptime?

Interestingly by chance I came across the same 34psi hot target on the OEM 4S just picking a number then going up or down by 2psi increments over about 4 total sessions 1st raceday. Unfortunately in my race I thought dropping out another 2psi would be faster but it was noticeably slower. 34psi worked on the 4S.
A combination of factors
I knew the good range was 32-36
And then i started to try.
I started 30psi cold and wemt 36-37 with the car sliding all around.
So i dropped to 34. Right on spot and best timing.
Then I say maybe i should drop more to go even faster.
Well at 32 i was 1 sec slower. With no grip.
So 34 is my happy land. Curios it is my happy land for many tires.
 
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Scootsmcgreggor

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BS1: two questions for you.

Maybe a stupid one but I’m no physicist so you never know. Let’s say your cold pressure results in 2psi over your hot target. Can you simply say next time drop your cold psi by 2 degrees and you’ll land right where you want? Or is it nonlinear?

Second question is about pressure climb in first two sessions (hpde). Let’s say for first session you achieve target hot temp. But some of the energy put into the system in the first session was in heating up components. I’ve found If you don’t drop pressure before second session you’ll overrun target hot temp. So is best practice to drop pressure between first and second sessions or drop pressure low enough before first session that target hot temp is not achieved until second session? Or am I way off altogether?

Thanks!
 

Bill Pemberton

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One other addition to the comments may be to list at what track you are running. The surface ( smooth, rough, asphalt, cement, etc. ) can also dictate the pressures as well as wear rates. This may help some folks determine which tire they might find preferable to others after we get a lot of input over the coming months. I am sure BS can comment on some of the tracks , as he has had the opportunity to run many around the US. I remember his comments on Sonoma and how it was a cheese grater , so hearing what tracks he feels are easy on tires and which are harder on the rubber donuts, I know I would find beneficial.
 

blacksheep-1

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BS1: two questions for you.

Maybe a stupid one but I’m no physicist so you never know. Let’s say your cold pressure results in 2psi over your hot target. Can you simply say next time drop your cold psi by 2 degrees and you’ll land right where you want? Or is it nonlinear?

Second question is about pressure climb in first two sessions (hpde). Let’s say for first session you achieve target hot temp. But some of the energy put into the system in the first session was in heating up components. I’ve found If you don’t drop pressure before second session you’ll overrun target hot temp. So is best practice to drop pressure between first and second sessions or drop pressure low enough before first session that target hot temp is not achieved until second session? Or am I way off altogether?

Thanks!

That's a can of worms..lol, generally speaking, when the tires..and I'm talking slick here, because that is what I deal with mostly, will generate more heat when new, I believe that this is because the tire tread is thicker, and also, the tire will have more grip. so you hit a little plateau before they get better at dissipating heat..that is why I liked the old
contis, they might be slow, but everyone had to run them, and they were consistent. Pirellis drop off like a cliff, the Michelins seem to be a mix of the 2.
How you gather temps and pressures is also important in that I have watched the Porsche come is, heat soak, and watch the pressures actually rise..so there are things like that.
You also didn't take into consideration the ambient and track temp between your 2 sessions, that might also be part of the problem.
To gather good data you have to have a consistent driver..not necessarily a fast one. but a consistent one. A good, fast one is always preferred however...lol.
If you start with a fixed set of numbers, go out, run about 3 laps, check the psi so it's someplace close, then go out a run serious lap times, that is the way to do it, the first laps are shakedown laps and really don't account for much, then correct from there.
So..to your point, the pressures are non linear, but they can be predicted.

Bill....Indianapolis, on the banking is the traction track from hell, the infield, not so much, and I think it's because those roads are used as service roads part of the time when not being used..but the actual oval..holy nuts!!
FWIW, I've " kissed the bricks" there on 2 occasions, once at the SCCA runoffs and once in Trans Am
 
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bob

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Second question is about pressure climb in first two sessions (hpde). Let’s say for first session you achieve target hot temp. But some of the energy put into the system in the first session was in heating up components. I’ve found If you don’t drop pressure before second session you’ll overrun target hot temp. So is best practice to drop pressure between first and second sessions or drop pressure low enough before first session that target hot temp is not achieved until second session? Or am I way off altogether?

Thanks!
Adjust any session's starting pressure to reflect your "pressure delta" to your hot pressure.
 

Scootsmcgreggor

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Adjust any session's starting pressure to reflect your "pressure delta" to your hot pressure.
So let’s say my cold to hot delta is 8*. Are you saying make sure your pressure before going out for every session is 8* below your target hot pressure? Wouldn’t that depend on how much heat is still in the system/how much cool off time you’ve had? Sorry if these are elemental questions I’m asking.
 

blacksheep-1

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So let’s say my cold to hot delta is 8*. Are you saying make sure your pressure before going out for every session is 8* below your target hot pressure? Wouldn’t that depend on how much heat is still in the system/how much cool off time you’ve had? Sorry if these are elemental questions I’m asking.
OK, I like to set my pressures first thing in the morning, that way the track and ambient temps are the same, it's the only time when they will be that way..so that's your constant. Set them so that when you go out you will be over your hot targets, then bleed them down when hot. Of course, you need to write this all down for future reference, once you establish that you've attained your hot target psi, then you only need to make adjustments for tuning, or a track/ambient temperature change, nothing else matters. The next morning, you will have a set of good cold pressures to work from, assuming the ambient/track is the same as it was the day before. If it is higher, or lower, you need to make that psi change to adjust to that, but your cold starting pressures are golden.
If you have to change tires, then I always have a backup set, ready to go and I adjust those to match the first set. IF you can't do that, then you have 2 choices,
1. set out both sets in the sun for an hour, stick them with a pyrometer to make sure the temps are close, then transfer the pressures from the old set to the new set.
or
2. use that delta you talked about, although that will be an educated guess because that method is not very accurate.
Basically, set them in the morning, and leave them alone.



 
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