Bmsluite
Bmsluite New Reader
8/9/22 6:18 p.m.

Alright so I want to know, from your experience, how long does it take for your tires to cool off after say, a 30 minute session on track?

 

I ask because tomorrow night my local track is having a 3 hour open session track night.  I have done 8 track days now but never an open session. Usually I have 40-60 minutes to sit around after each 20-30 minutes while my car cools off.  Tomorrow I won't have that. 

 

I run 340 TW Michelin PSS *BMW (the ones off an M3) on my 07 350Z (3200 lbs.).  I like these because I can push the car right to the limit and it's fun because they let go really easy and I can just play around with the chassis.  I know they are not a track tire.  This is why I worry about them overheating and delaminating (I did this with some other tires).  At $1370 a set.... Not what I want to do. 

 

How long should I give the tires between each session to cool down in the three hours?

 

I spray the edges with water after each session.  This lowers the temperature much faster some old guy told me one day. 

codrus (Forum Supporter)
codrus (Forum Supporter) GRM+ Memberand PowerDork
8/9/22 6:25 p.m.

Tires cool pretty quickly, enough so that if you want accurate tire pressures you check them in the pit lane after a hot lap.  Doing a cool down lap and checking them in the paddock after you get out yields numbers that can be 1-2 psi lower.  You can probably keep the tires OK without even coming in by just doing a slower cooldown lap every N hot laps.

One of the other things to be concerned about when doing extended sessions like this is transmission and differential temperatures.  I dunno if that's specifically a concern with the Z, but in general endurance race cars often have coolers installed on them to avoid destroying bearings with heat.

 

Bmsluite
Bmsluite New Reader
8/9/22 7:16 p.m.

In reply to codrus (Forum Supporter) :

Awesome info, that's what I was looking for.

 

So I asked my other buddy about the diff and trans.  He says the trans are solid as guys Enduro race these things on the stock trans with no coolers.  The diff I have extra capacity cover with a boat load of fins build in.  Got an OS Giken unit back there so I really wanted to protect my investment.

codrus (Forum Supporter)
codrus (Forum Supporter) GRM+ Memberand PowerDork
8/9/22 7:20 p.m.

Re-reading your original post, I should note that I've never tried extended sessions like this on a genuine street tire like a Michelin PSS.  Semi-race tires (NT01s, RS4s, etc) do fine with extended running with just occasional cooldown laps.  Full depth street tires might be different -- I'm kinda waffling on this. :)

 

 

 

 

Bmsluite
Bmsluite New Reader
8/9/22 8:18 p.m.

In reply to codrus (Forum Supporter) :

Yeeaahhhh I still don't know... I packed the car up with the track box.  I'll drive it to work. I have until noon tomorrow to sign up.  In hindsight I should have just gotten the Goodyear SC3 tires. Problem is it's usually cold here so the PSS let me drive it a few more months a year.   One day I'll get another set of wheels for track tires

Take a sprayer 

Tom1200
Tom1200 UberDork
8/9/22 8:46 p.m.

 I once did an event with a 6 hour window; I pretty much did 30 minutes on and 20 minutes off.

Bmsluite
Bmsluite New Reader
8/9/22 9:21 p.m.

In reply to Tom1200 :

What tires were you running? 

codrus (Forum Supporter)
codrus (Forum Supporter) GRM+ Memberand PowerDork
8/10/22 12:44 a.m.
Bmsluite said:

Yeeaahhhh I still don't know... I packed the car up with the track box.  I'll drive it to work. I have until noon tomorrow to sign up.  In hindsight I should have just gotten the Goodyear SC3 tires. Problem is it's usually cold here so the PSS let me drive it a few more months a year.   One day I'll get another set of wheels for track tires

If it were me I'd go do the event, run about a 50% duty cycle (20 on, 20 off, say) and keep an eye on the tires.  If they start getting greasy then don't continue to abuse them, do a cooldown lap and come in to inspect.

Bmsluite
Bmsluite New Reader
8/10/22 6:52 p.m.

In reply to codrus (Forum Supporter) :

I opted to not go.  Next track day I will check temps in 5 minute increments after a run to see how fast they cool down.  Running around trying to time sessions out for 3 hours so my stuff doesn't get destroyed didn't sound like a ton of fun.  I am just going to go fishing tonight instead lol.

jfryjfry
jfryjfry SuperDork
8/10/22 6:56 p.m.

You'll be fine with the tires.  They won't give you trouble.  Other things might need more time to cool off but not your tires

Berck
Berck Reader
8/10/22 7:43 p.m.

I don't think those tires will be much of a problem.  I've abused some (presumably similar?) PSS pretty badly on my Focus RS, but sadly only for about 25 minutes at a time because at that point the oil temp is 290F and the AWD system has disconnected.  They got a bit melty, but no problems with another couple years of street use.

And tires cool off really fast.  A single cool down lap dramatically changes race tires, and after about 10 minutes they go from being goo that'll pick up huge rocks to pretty solid again.

I once did 2 tanks of gas in a Miata on Toyo street tires, only really stopping to fill up the tank.  They were used up, but fine.

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