Slow Leak in a Tire - HPDE?

[dmw16]

I noticed this morning that one of my tires on my car is flat. It's a slow leak, but I'm not sure the source.

Assuming it's a slow leak and could normally be patched on a street-used tire, can I either 1) patch it or 2) just keep an eye on the pressure and use it for HPDE's?

If the tires were past 50% life I'd just toss them both, but they only have 3 track days on them so I was hoping to save them. I really don't want to replace just one.

Thoughts?

[///M Ryder]

I wouldn't risk it......look for the leak. It could be as simple as the valve stem. If it's any other area I would replace it. Better to replace a tire than a car.....or worse.........Phil

[dmw16]

Originally Posted by ///M Ryder

I wouldn't risk it......look for the leak. It could be as simple as the valve stem. If it's any other area I would replace it. Better to replace a tire than a car.....or worse.........Phil

I put air in it and we'll see if it's still holding tomorrow. I am hoping it was coming from the valve stem. One of the others was giving me trouble before. If it's leaking from elsewhere I'll be replacing it.

Can I get away with replacing just one tire? I really wanted to use these up and then switch to an 18" square setup, but I don't want to discard 3 good tires.

[ThunderMoose]

I'd replace at least a pair depending on wear. Hopefully it's the valve stem.

[dmw16]

Originally Posted by ThunderMoose

I'd replace at least a pair depending on wear. Hopefully it's the valve stem.

The tires have about 750 miles on them. Unfortunately some of it is 3 days at Summit Point. I'm inclined to replace the pair as well.

[Porschefile]

I'd run it unless it is punctured somewhere visible. I don't know what kind of tire it is, but slicks tend to suck at holding air long term.

[dmw16]

Originally Posted by Porschefile

I'd run it unless it is punctured somewhere visible. I don't know what kind of tire it is, but slicks tend to suck at holding air long term.

It's a Michelin Pilot SuperSport. It's lost about 1.5# in about 14 hours.

If it's safe to run then I'd like to but isn't not something I want to risk if there's a chance of failure. I may take it off the car and see if I can find a puncture, but I don't hear or feel anything.

[Porschefile]

I'd run it by a tire shop and get them to dismount it and see what's going on. I have ran plugged tires on tracks multiple times without consequence and I drive fairly hard.

[dmw16]

I took it to the local tire place. We will see what they find.

[dmw16]

Turns out it was leaking from around the bead.

Not sure if I ran too much or too little pressure at my HPDE (38psi cold) and caused that or it just happened.

[Porschefile]

Originally Posted by dmw16

Turns out it was leaking from around the bead.

Not sure if I ran too much or too little pressure at my HPDE (38psi cold) and caused that or it just happened.

That sounds way high to me. I ran 30-32 cold on AD08 with good results. You'll trade grip for tire edge wear though. 38 cold will be near 50 hot, which is super high!

[dmw16]

Originally Posted by Porschefile

That sounds way high to me. I ran 30-32 cold on AD08 with good results. You'll trade grip for tire edge wear though. 38 cold will be near 50 hot, which is super high!

Thanks. Someone had suggested running pretty high and since we had a cool down lap I'm not sure how high they got on the track.

I'll run around 30 next time out.

[Porschefile]

Originally Posted by dmw16

Thanks. Someone had suggested running pretty high and since we had a cool down lap I'm not sure how high they got on the track.

I'll run around 30 next time out.

If you're used to 38 might want to try 32 first and see how the wear is. If you drive the car hard with low pressures it will eat your outside edges w/o proper camber. Just trial and error!

Higher pressures are more of an autocross thing, where the tires never get to temp anyway.

[dmw16]

Originally Posted by Porschefile

If you're used to 38 might want to try 32 first and see how the wear is. If you drive the car hard with low pressures it will eat your outside edges w/o proper camber. Just trial and error!

Higher pressures are more of an autocross thing, where the tires never get to temp anyway.

I have camber plates but I'm only running about -2.7 deg.

I will try 32 for my next go and see how that is.

[S65V8]

Originally Posted by dmw16

I have camber plates but I'm only running about -2.7 deg.

I will try 32 for my next go and see how that is.

Just measure the hot pressures right after you come off the track (no cool down lap, and do from pits if possible), and manage the pressure from there. I've found 37 - 38 to be my sweet spot. I start at 30 and still have to pressure down from 40.5 - 41 off the track...

Starting at 38, wow, must of been pretty darn high coming off the track like Porschefile said.

[signes]

38 cold, wow. You must have been sliding all over the place. AD08s gain a lot of pressure quickly. Agree with Porschefile, 30-32 cold would be a good starting point.

[dmw16]

Originally Posted by signes

38 cold, wow. You must have been sliding all over the place. AD08s gain a lot of pressure quickly. Agree with Porschefile, 30-32 cold would be a good starting point.

I wasn't sliding all that much, but I also probably wasn't going all that fast being it was my first HPDE. I will start much colder next time.

[krnnerdboy]

Did the tire place debead the tire and reinstal? Last time I was leaking from the beads, it was caused by rocks getting in there when in had an off road session at the track

[dmw16]

Originally Posted by krnnerdboy

Did the tire place debead the tire and reinstal? Last time I was leaking from the beads, it was caused by rocks getting in there when in had an off road session at the track

Yes, they did a full remount and balance.