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Tire Pressure Loss

I have a slow leak in my right front Conti take-off. My first session on the this tire will be tomorrow. It appears to be losing a little less than 1/2 a pound an hour. Do I dare run on this tomorrow? My pressure setting is 25.5 cold.
 
Slicks can do that. Hoosier even mentions it on their site.......maybe in the FAQ section? I have had it before. Inspect the tire well and make sure there's no damage.
 
Thanks Gary. I just double checked the tire and it is very clean, in fact one of the cleaner take offs I have received. It is on the trailer however so I will need to look at it again after I get it off and keep a close eye on it before and after each session. Surprisingly the last couple of hours it has held right at 20 lbs.
 
1,281
3
Tulsa, OK
I have had an R6 do this. I just kept a close eye on the pressure after each session and rolled with it (no pun intented ::)) Ran it with no issues for several days.
 
Most common leaks are bead or valve stem. Easy to check, put a drop of water in the valve stem and watch for bubbles. Same for bead, lay it flat, put enough water in the bead to cover it and watch for bubbles. Low loss like that should be fine though for short events.
 
LS110 said:
I have a slow leak in my right front Conti take-off. My first session on the this tire will be tomorrow. It appears to be losing a little less than 1/2 a pound an hour. Do I dare run on this tomorrow? My pressure setting is 25.5 cold.

John how did you make out with the tire? I did not say anything because Gary answered your post. Still I would worry about a tire losing that much pressure in a short time. Most of mine go completely flat (off the car anyway) between events but that is normally a month or more.

You are driving way harder then me with that cold pressure. I start 27-29 depending on conditions looking for about 40 front and a little less in the rears. What is you target hot pressure?
 
The tire progressively lost air faster through out the day and I replaced it after my third session for fear it was dropping too fast.

As it turned out, my right tire was not my biggest issue today as I blew out my left front. I have been having a problem with left front tires all season and this is my 4th blown left front this year, and non last year. I did go to a 3.2 negative camber this year, however I just looked up Hoosier's camber recommendations and it is 3.0 and never less than 2.5. Maybe it is a combination of the lower pressure the 3.2 camber. I have triple checked for anything in the wheel well that could be damaging it.

I typically run 30 to 32 hot. Scott - what are you running hot? Sounds like 27 to 29 cold and I am 25 to 26 cold.
 
That is way low for these tires IMHO. I try for about 39-40 front and 37-39 rear hot pressure on a dry track running hard. You need to bring the camber in to -2.8/3.0 as far as I have been told. I need to have some work done to get more camber since my is maxed at 2.6.

Still your pressure is way low, I would like to see a picture of the tires, the blown and the others. Are you getting more wear on the inside/outside vs. the middle? Have you taken any temp reading?
 
YellowBoss said:
That is way low for these tires IMHO. I try for about 39-40 front and 37-39 rear hot pressure on a dry track running hard. You need to bring the camber in to -2.8/3.0 as far as I have been told. I need to have some work done to get more camber since my is maxed at 2.6.

Still your pressure is way low, I would like to see a picture of the tires, the blown and the others. Are you getting more wear on the inside/outside vs. the middle? Have you taken any temp reading?

Below is a photo of today's blown tire. The previous tires were too destroyed after the blowout to tell much, other than the fact my installer told me the bead was intact on each of the previous. The last two failures were clearly on the inside of the tire, as this photo shows. I have not taken temp readings and need to buy a device to do this. Recommendations of what to buy would be welcomed.

blowntire_zps6cc80982.jpg
 
LS110 said:
Below is a photo of today's blown tire. The previous tires were too destroyed after the blowout to tell much, other than the fact my installer told me the bead was intact on each of the previous. The last two failures were clearly on the inside of the tire, as this photo shows. I have not taken temp readings and need to buy a device to do this. Recommendations of what to buy would be welcomed.

Need to see the face John, also tell me how the wear marks are - even across, worn on both edges, just one edge, middle etc.. I would also like to see a close up of the blown and non-blown tires on the outside edge.

You can spend big bucks for a contact temp gauge but I just use a non-contact type from Harbor Freight. For non-race stuff it works fine. If Rob does not see this thread PM him and ask about what gauge might work well (blacksheep1).
 
Here are 5 more photos of the tire. You can see the heavy wear on the inside section and the cording that occurred. The wear appears fairly even across the rest of the tire surface with the exception of the last 1" of the inside edge where it corded. I have also been discussing this problem with Gary who has a very similar set-up as mine, with slightly less camber, 2.7 this year and 3.0 last year, and runs 32 to 34 hot. Again I am at 3.2 and 30 to 32 hot.


photo5_zps71494eda.jpg

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All right, take this for whats it worth, I am not an expert on tires. However after running these for a while and taking advise from Rich Martin and others on Dean's crew and lately from site member Rob I have a little knowledge about these. Here is a Grand Am take-off used by me at Sebring for two full hard days.
SebringTirewear_zps3d3b9df6.png

I need you to email me some pics, the res is way too low to see anything here.

I have not seen a Conti edge corded that bad except on a car with front end damage from a wreck. First thing you need need to do is look for hot pressure in the high 30's, up to 40 is ok and running all four the same hot is fine, I just like a little softer tire in the rear.

Next double check the toe, if that is off (out) it could be adding to the extra recommended camber and low pressure. Try zero toe with about -2.8 -2.85 camber. If that works you can always bump back up the the recommended -3.0. I would stay away from toe out until you get this under control. I am running 2.6 and would go more but need to modify for that but look at the results, slight toe out. Sometimes you can not just take the setting the race cars use because there are different ride heights and other things.

I have always has hotter temps on the inside edge in general but good clean even wear. Certain tires in the Daytona banking have shown a little inside edge wear over the middle and outer. Judging by the first pic you posted the inside is getting so hot, along with wear, that it blew out. Try what I said, I hope it will help you and send me the pics.

Edit: Send pics like the one I posted of the wear dots and also the side wall inside and out.
 
Here's the info I was given from Capaldi Racing for my car with the Continental's on. FYI, my camber is set to 2.5 degrees. Start at 32 psi cold tire pressure and run 38 psi hot. I ran my car this past weekend for three 15 minute sessions with no issues.
 
wwilde001 said:
Here's the info I was given from Capaldi Racing for my car with the Continental's on. FYI, my camber is set to 2.5 degrees. Start at 32 psi cold tire pressure and run 38 psi hot. I ran my car this past weekend for three 15 minute sessions with no issues.

Sounds good on the hot. Cold seems a tad high as I get an ten-eleven pound increase, sometimes more on the left at a right hand track.
 
Thanks for the input guys. I will get some more pics taken tomorrow with higher res.

My car is also going into the shop tomorrow and will go with the 2.85 camber. Last year my problem was cording on the outside edge and that is when I changed from 2.7 camber to what I believe is 3.3.

I am surprised by the 10 pound gain received when hot as i typically experience about 6 pounds. I will try the 32 cold, to get to 38 to 40 hot. I would like my rears a bit softer and thus may just go 30 for them.
 
LS110 said:
I have a slow leak in my right front Conti take-off. My first session on the this tire will be tomorrow. It appears to be losing a little less than 1/2 a pound an hour. Do I dare run on this tomorrow? My pressure setting is 25.5 cold.

Some good info in this thread. I will say though that slicks tend to leak and its perfectly normal. The side walls only have enough rubber to stick the cords together and air will leak through them. The rule of thumb is if the tires leak down more than 3 psi an hour, don't race on them. You can however practice on them as long as they don't leak down more than 5 psi an hour. You should verify that you don't have a leak in your rim if this is a recurring thing. Also, your hot pressures will vary depending on how much moisture is in the compressed air you use. Be sure to drain the water from the compressor tank before filling tires and use a nice in line water vapor filter with your compressor system.
 
John, here is a Rolex take-off 285 with a full day on it. I know it is not a front like your 285's but wanted to show you the wear at higher pressure. I have read on some other forums of guys running the Rolex tires lower but the higher pressure is working well for me. These were 37.5 PSI hot, I get about a 10 PSI increase in the rear tires. (FYI I was seeing a 13-14 pound increase in the Front CTSCC 275's today)

CIMG4272_zps25d6db12.png
 
Scott - Thanks for posting that photo and I keep forgetting to post some added photos of mine. And now when I am thinking about it, I am not in a place to do it as the photos are on my home computer and I am at our cabin.

Your wear appears to be very even across the tire. Are you taking temps of the tire and if so, what do those show? A week from tomorrow I am back at the track and going to try 36 to 38 hot and see what I think. I did get my camber changed to 2.9 so hopefully between these 2 items I have solved my blow out problem.

I have 2 sets of tires to test this on next week and am going to try both to see which I like better. I just received another set of Conti GT"R" take-offs (Rs front and rear) and I bit the bullet and bought a new set of Hoosier slicks, R80 fronts and R100 rears. The Hoosiers are spendy and am hoping I actually find the Conti's to be just as good or better.
 
Zquez said:
Some good info in this thread. I will say though that slicks tend to leak and its perfectly normal. The side walls only have enough rubber to stick the cords together and air will leak through them. The rule of thumb is if the tires leak down more than 3 psi an hour, don't race on them. You can however practice on them as long as they don't leak down more than 5 psi an hour. You should verify that you don't have a leak in your rim if this is a recurring thing. Also, your hot pressures will vary depending on how much moisture is in the compressed air you use. Be sure to drain the water from the compressor tank before filling tires and use a nice in line water vapor filter with your compressor system.

The tire that had the slow leak survived 4 sessions, each session I was adding more air to keep it 30-32 hot. The 4th session did it in however and after the session, while not blown, the tire measured 4 lbs. How is that for lucky that it did not blow. Thankfully that was a right front that does not take nearly the punishment of my left front. I obviously replaced the tire at that point. I will find out this week if it is the rim as I have mounted a new tire back on that rim.
 

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