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I'll try my next set at 30 cold but shooting for 36-38 hot in a 3150 pound car at places like VIR and NJMP means 30 cold is really tough. Anything above 38 in my car and the rear end is all over the place and 30 cold brings me in at 44 hot by the end of a Sprint race... By the second or 3rd session we are 28 cold 36 hot.
I'll totally admit we are well below 30 cold on mine so cold tearing is possible but will also say it hasn't affected the longevity or cycles on any of my sets either. It's just something we noticed but ignore.
why is it "tough " for 30psi cold? i think anyone that is shooting for 30psi hot, starts out about 23 to 24psi. Ive never heard of a 14psi pressure change based on the amount of heat that can be generated by the tires and wheels.
Don't confuse As with Rs. They are a different tire.
I was speaking to both. i use the As, but the racers in our group all drive the Rs. i wonder what the defect is caused by. is it true that both the As and the Rs share the same construction, but the compounds are different. if so, you would think that the As would share the same issues. so, maybe there are differences.
why is it "tough " for 30psi cold? i think anyone that is shooting for 30psi hot, starts out about 23 to 24psi. Ive never heard of a 14psi pressure change based on the amount of heat that can be generated by the tires and wheels.
I hate to engage with you on this, but yes, you can have a 14 psi change.
Matt [Muller] - hey fella! - yes have seen Hoosier's recommendations. We usually start cold in the range of 27-28 depending on the ambient, track surface, setup, etc.
The challenge is keeping the hot pressures below 41-42 psi by mid-sprint, especially in the rear. Beyond that the car gets pretty lively in ze back end.
Would be great if PCA would let us use auto bleed valves....
Matt [Muller] - hey fella! - yes have seen Hoosier's recommendations. We usually start cold in the range of 27-28 depending on the ambient, track surface, setup, etc.
The challenge is keeping the hot pressures below 41-42 psi by mid-sprint, especially in the rear. Beyond that the car gets pretty lively in ze back end.
Would be great if PCA would let us use auto bleed valves....
Hey Bud, long time, no talk. My medical hell continues, but that's for another time.
I agree with you all about what hot temps become if you start at 30. This was not what I was commenting about. I was more commenting on the fact that the manufacturer has pretty specific instructions on use and when followed, the tires are fine and when not followed, issue's arise. This is exactly what the manufacturer states will happen in their care and use instructions so point is, no one should be surprised.
We tried bleed valves on DE car's. Their hype turned out to be much better than usage experience. But maybe it was the brand we tried.
I hate to engage with you on this, but yes, you can have a 14 psi change.
It was an honest question. How is that possible. I think your tires would have to near 250 degrees for that to happen.
Originally Posted by jdistefa
Matt [Muller] - hey fella! - yes have seen Hoosier's recommendations. We usually start cold in the range of 27-28 depending on the ambient, track surface, setup, etc.
The challenge is keeping the hot pressures below 41-42 psi by mid-sprint, especially in the rear. Beyond that the car gets pretty lively in ze back end.
Would be great if PCA would let us use auto bleed valves....
thats seems to be way too much pressure. why not start out at 23-24psi like we all do.??? as you can see below, if you started out at 34psi, you could get to near 40psi if you got temps from 34 at 70degrees, to 40psi at 170degrees. i doubt you can get much more than 170 surface temp, let alone interior air temps in your tire. but, if you can.... i would like to know how. ...im not trying to argue with you . just want to know how this is possible, as i could be missing something here.
Bleeders had something to do with the "Cleanliness is next to Godliness" quote. They are very finicky and not easy to work with all the time.
250*F air temp inside a wheel is not uncommon and can be done on a lot of cars. There are a lot of factors that go into it.
well, that seems quite high. haven't seen that on any cup cars that I've measured temps in the hot pits, however it is gas law, so if it happens, you have to be right .. if you measure 14psi change, then for sure, the interior temps need to be near 250 degrees. maybe the smaller tires get more heat in them? the transam guys hae heavier , more powerful cars, stickier tires, and they start out at 18-20 psi and end up in the 28psi range.
It was an honest question. How is that possible. I think your tires would have to near 250 degrees for that to happen.
thats seems to be way too much pressure. why not start out at 23-24psi like we all do.??? as you can see below, if you started out at 34psi, you could get to near 40psi if you got temps from 34 at 70degrees, to 40psi at 170degrees. i doubt you can get much more than 170 surface temp, let alone interior air temps in your tire. but, if you can.... i would like to know how. ...im not trying to argue with you . just want to know how this is possible, as i could be missing something here.
14 PSI change is easy and my internal tire temp sensors regularly read 90C+ so ~ 212 degrees and we see 220 pretty often. I DO go out 24 cold to get a 34-36 hot... I was replying to Matt that I would "try" 30 cold as that is what Hoosier recommends but I know 30 cold is 44 hot by mid sprint and the rest of the race is tire management as the rear end is all over the place. It would take 3 or 4 bleeds to get down to 36 hot from 30 cold. Especially at a VIR or NJMP where tarmac temps are in the 140 range... So your tires are only 30 degrees warmer than the track surface?
Most of us here having this discussion are also driving mid or rear engine remember, a 3,000 pound front engine car is very different to a 3,000 pound mid or rear engine car when you start to talk about rear tire temps unless you have the same corner weights as us as well...
If you want to know how to do it go watch my videos, there is no secret sauce, this is what MY car does... Not trying to be a wise *** but really not sure what else to tell you other than watch the video. How am I doing it? Throttle, brake and steering wheel combined with slip angle, I'm guessing...
I also want to say, I haven't had any issues with the tires at all, no dropoff, no separation, no difference in feel, longevity anything... It's more of a visual thing that "looks" like a fender rub but isn't on every set I've had this year. No issues with the tires at all though, purely something we noticed. We wrote it off as a change to how they are gluing together the sidewall and just ignored it.
well, that seems quite high. haven't seen that on any cup cars that I've measured temps in the hot pits, however it is gas law, so if it happens, you have to be right .. if you measure 14psi change, then for sure, the interior temps need to be near 250 degrees. maybe the smaller tires get more heat in them? the transam guys hae heavier , more powerful cars, stickier tires, and they start out at 18-20 psi and end up in the 28psi range.
Moisture is the big unaccounted for and hard to measure part of pressure growth. When I'm doing tires, I can pick the sets out that were not bled by the same person on most days. (Almost) All the NASCAR stuff is mounted in a climate controlled warehouse anymore and then controlled tightly after that.
Track temps, brake temps, tire construction, and lots of other things have big effects on how a tire builds heat.
Moisture is the big unaccounted for and hard to measure part of pressure growth. When I'm doing tires, I can pick the sets out that were not bled by the same person on most days. (Almost) All the NASCAR stuff is mounted in a climate controlled warehouse anymore and then controlled tightly after that.
Track temps, brake temps, tire construction, and lots of other things have big effects on how a tire builds heat.
Please hold for Kibort's latest temp vs. moisture vs pressure graph, where he'll try, despite a ridiculously complex, and Likely made up graph, that he's crunched the numbers and feels he's correct.
Please hold for Kibort's latest temp vs. moisture vs pressure graph, where he'll try, despite a ridiculously complex, and Likely made up graph, that he's crunched the numbers and feels he's correct.
for this discussion, we are only talking about a 10% change in pressure ... so i left it out. in other words, for someone non technical like you, its about a 2 psi pressure change with air vs a dry air. btw, its never that complicated.. you just see it that way!
Originally Posted by Matt Romanowski
Moisture is the big unaccounted for and hard to measure part of pressure growth. When I'm doing tires, I can pick the sets out that were not bled by the same person on most days. (Almost) All the NASCAR stuff is mounted in a climate controlled warehouse anymore and then controlled tightly after that.
Track temps, brake temps, tire construction, and lots of other things have big effects on how a tire builds heat.
yes, as i mentioned to Morsini, i left that out but it certainly will raise the end pressures vs a ideal, dry air fill. the point was, i have never heard of or seen a 14psi pressure rise on tires at the track. i would suspect if it was possible, it would be on some 1000hp , 200mph ,, tire melting beast. im not arguing that tire pressures can change due to all sorts of inputs... im just saying or actually, asking, how 14psi was possible on a porsche wearing DOTs and near stock HP.
Originally Posted by Paul Solk
14 PSI change is easy and my internal tire temp sensors regularly read 90C+ so ~ 212 degrees and we see 220 pretty often. I DO go out 24 cold to get a 34-36 hot... I was replying to Matt that I would "try" 30 cold as that is what Hoosier recommends but I know 30 cold is 44 hot by mid sprint and the rest of the race is tire management as the rear end is all over the place. It would take 3 or 4 bleeds to get down to 36 hot from 30 cold. Especially at a VIR or NJMP where tarmac temps are in the 140 range... So your tires are only 30 degrees warmer than the track surface?
Most of us here having this discussion are also driving mid or rear engine remember, a 3,000 pound front engine car is very different to a 3,000 pound mid or rear engine car when you start to talk about rear tire temps unless you have the same corner weights as us as well...
If you want to know how to do it go watch my videos, there is no secret sauce, this is what MY car does... Not trying to be a wise *** but really not sure what else to tell you other than watch the video. How am I doing it? Throttle, brake and steering wheel combined with slip angle, I'm guessing...
i can understand a 10psi change, on a smaller tire than the OP brought into the discussion, is possible. if you see it, i believe you.. ...........but when you talked to matt about the 30 cold pressure and saw a 14psi change,i was wondering how that was possible as it clearly is beyond what would be expected by temps generally seen internally to the tire. you are seeing 220 internal temps. you have temp sensors in the tire, right (not just IR measurements on the tread) where do you measure internal tire temps? is it a internal rim surface temp or actual air temp??
now you ask about the track surface , which generally can easily be 100 to 140 degree depending on the day. that's a complicated interactive factor. the heat in the tire, is mainly from friction and dynamic distortion, as well as one of the major factors, rim heating. my rims will get near 200 degrees, and this can heat the air in the tire too. if you have solid rotors that heat from the rotor goes directly into the hubs and feeds the rims. yes, on a 100 degree day, with track temps of 130 to 140 F, yes, tire temps IR readings in the hot pits are near 170F. dont know what the internal temps are, as i can calculate that easily via Gaslaw. they go up about 7psi. one of the reasons, if you think about it.. there is 100mph air flow hitting the tire, after it has made contact with the 140degree surface. rubber is a great insulator, and doesnt transfer heat well.. again, most all of the heat is created by friction, and the constant distortion of the rubber, as well as the rim heat.. go check your rim temps next time you are at the track..
no, the balance of the car is a small factor. what you see on the rears, we might see on the fronts (actually more so as there is more power used in slowing on the fronts , of a front engine car, than a rear engine car). also, we are talking about higher HP front engine cars that can actually get a weight transfer to the rear that can create more heat in the rears as well..
not arguing with you . just was curious how you could get that much heat to create that much of a pressure change. By the way, the OP has a Vet that was in discussion not a rear engine car and much larger tire sizes . maybe the reason you are seeing the higher temps is due to the smaller sizes working harder.
for this discussion, we are only talking about a 10% change in pressure ... so i left it out. in other words, for someone non technical like you, its about a 2 psi pressure change with air vs a dry air. btw, its never that complicated.. you just see it that way! yes, as i mentioned to Morsini, i left that out but it certainly will raise the end pressures vs a ideal, dry air fill. the point was, i have never heard of or seen a 14psi pressure rise on tires at the track. i would suspect if it was possible, it would be on some 1000hp , 200mph ,, tire melting beast. im not arguing that tire pressures can change due to all sorts of inputs... im just saying or actually, asking, how 14psi was possible on a porsche wearing DOTs and near stock HP.i can understand a 10psi change, on a smaller tire than the OP brought into the discussion, is possible. if you see it, i believe you.. ...........but when you talked to matt about the 30 cold pressure and saw a 14psi change,i was wondering how that was possible as it clearly is beyond what would be expected by temps generally seen internally to the tire. you are seeing 220 internal temps. you have temp sensors in the tire, right (not just IR measurements on the tread) where do you measure internal tire temps? is it a internal rim surface temp or actual air temp??
now you ask about the track surface , which generally can easily be 100 to 140 degree depending on the day. that's a complicated interactive factor. the heat in the tire, is mainly from friction and dynamic distortion, as well as one of the major factors, rim heating. my rims will get near 200 degrees, and this can heat the air in the tire too. if you have solid rotors that heat from the rotor goes directly into the hubs and feeds the rims. yes, on a 100 degree day, with track temps of 130 to 140 F, yes, tire temps IR readings in the hot pits are near 170F. dont know what the internal temps are, as i can calculate that easily via Gaslaw. they go up about 7psi. one of the reasons, if you think about it.. there is 100mph air flow hitting the tire, after it has made contact with the 140degree surface. rubber is a great insulator, and doesnt transfer heat well.. again, most all of the heat is created by friction, and the constant distortion of the rubber, as well as the rim heat.. go check your rim temps next time you are at the track..
no, the balance of the car is a small factor. what you see on the rears, we might see on the fronts (actually more so as there is more power used in slowing on the fronts , of a front engine car, than a rear engine car). also, we are talking about higher HP front engine cars that can actually get a weight transfer to the rear that can create more heat in the rears as well..
not arguing with you . just was curious how you could get that much heat to create that much of a pressure change. By the way, the OP has a Vet that was in discussion not a rear engine car and much larger tire sizes . maybe the reason you are seeing the higher temps is due to the smaller sizes working harder.
Sarcasm, quite like the ideal gas law escapes you.
Can't wait for this to go fifty plus pages with you presenting all manor of charts and graph about how you're correct and it's not real, even though ten people have told you it is and you're wrong. Can't you see the pattern in your behavior? When will you get the help you so desperately need?
09-17-2018, 09:46 PM
