mark kibort

Dont be an idiot. learn to read and comprehend Mikey. Look, i was curious as to the reasons and temp readings of why/how someone saw 14psi. I know gas law well, and i dont think you do........because a simple chart like what i posted , even referencing a similar tire size, shouldn't confuse you . the only reason this part of the discussion will go on further , if more idiots join in , not understanding the question i asked. in other words, there is nothing to be "correct" about. i was stating clearly that 14psi would require more temp than most see. he responded with questions about how 30 degrees over road temps is odd. clearly it is HE that doesn't understand some basic laws of thermodynamics, BUT, clearly stated he saw very high temps in his tire, which would follow gas law and be a reason for his high pressure changes.

Just a note for DE guys like you from someone with about 20 years of doing this (99% racing) . NOT MANY at the track, even with track temps of near 140 degrees, have ever seen pressure changes of 14psi its usually about 10 (generally).. do you disagree? and if you understand gas law and see when i come in from a 24psi set pressure and end up at 30psi, that can easily be used to show the temp change of the tire's air. i also added wheel temps and their source of heat driven by brake heat, beyond the tire. this is a factor too)

why are you being so argumentative? did your mommy not give you enough love? i think it is YOU that needs to see someone. I'm just asking a simple question and i think i got the answer anyway. ( he said he had tire air temp readings of over 220degrees, .. then what he saw would be correct) this is not complicated Mike.

the_vetman

I won't get into an argument and several posts were TLDR, but I will verify that I regularly get OVER 10 psi hot pressure jumps. For example, I start at 26 psi then end up at 38 hot (too high for me). And that's just DE, not racing. Paul is a very fast driver so I do not doubt AT ALL that he's seeing 14 psi jumps.

mark kibort

We are talking hoosiers, are you? Maybe its the small size that might be a difference. could be more moist air ... i assure you , I'm going faster than Paul, in a heavier car with more power, so its not a speed thing. It's the reason i asked. In my group of the fastest car out there at the club races, we are not seeing more than about 7-8psi pressure change and im curious as to why . Ill have to ping my spec miata friends to see if they are seeing higher pressure rises. Also, overdriving the tires can introduce a lot more heat too.. there are a lot of factors. its a side issue.. MIke is making it into a fight. i agree with Paul, if he is seeing 220 internal tire air temps, then that explains much of it. my only question is how. not a fight. just a question.

the_vetman

Much less pressure gain in my Spec Miata - definitely less than 10 psi. SMs are much lighter and we don't brake much, so less heat transfer to wheels and tires. Similar driving style - aggressive.

mark kibort

again, we are getting a little off topic, but Ill play. again, we have seen all the heavy cars, that are faster, and more powerful.. run near 8psi pressure rise. much faster than your spec miata and any light boxster. as far as what causes heat, its side wall deformation, and tread deformation, which is the majority of the heat. im sure the braking and rim heating would be part of the addition to heat in the tire. I dont know how much, BUT with the fact that the larger heavier cars , running less than 10psi change, with up to 10x the power, near 50mph higher top speeds, and much higher lateral accelerations, it's why i asked the question
as a note, as you bring up a good point and is referenced to something i brought up earlier.... My rears and fronts have the near same pressure rise.. my fronts obviously have a LOT more braking heat, but the rears have acceleration loads too, and maybe more tire slip... in the end, they seem to be heated the same.. . One of the main reasons for this is much of the heat is dissipated by the rotor before it hits the hub, even more so with 2 piece rotors. (just a side note on that) by the time i get in the pits, the rotors hit max temps of near 1400degrees, but in the paddock, after a min or so, the rotors are 5-600F. with the rear rotors being in the 350F range... and the rims for both being in the 175 range.. showing a lot of that heat is dissipated by the rotors themselves. I also did a test of how long the pressure takes to go down IN the tire.. 15mins later, they only lost 1psi.....so its easy to measure and this shows what the temp decay is as well.

This reminds me of the " lighter car is easier on brakes with same power" discussion. lots of factors. again, i was just curious. we all know or have heard of gas law. if you are seeing 14psi pressure rise, there has to be the temps to match it... i was asking how that is possible since i haven't seen that on heavier more powerful cars like the Vet and my car that are using the sizes in the discussion from the beginning.

Matt Romanowski

I haven't read all the other stuff here, but if you started at 75F ambient and ended up at 250F hot air, you would go from about 26 psi to 40 psi. That is certainly possible on a hot sunny day, hot track (I've never seen anywhere near 140F track temps Mark mentioned), heavy car, and certain tire constructions.All in my experience.

Not the same, but remember NASCAR short track cars can set the bead of a tire on fire.

991carreradriver

From the Hoosier site, that Matt posted from, I just noticed this:
Banked Oval / Road Courses

"Hoosier DOT radials are not intended for high banked super speedway or high speed and banked tracks like Watkins Glen International, however on these type of course configurations with the proper settings the tires can be used. In these situations, the loaded side tires should be elevated five (5) psi cold and hot above the normal road course pressure recommendations. Camber settings should be reduced to or below -2.0 degrees."

mark kibort

yes, most of the "specs" dont really match reality. those specs are done with research and actual driver results, coupled with risk analysis. in reality, NO one pays any attention to the warning and most ever single car was on hoosier A series tires (A7s) and most all of us, increased the pressure by about 2-3psi ONLY on the outside tires. the only blow outs i saw that weekend was from guys on slicks. watkins glen had nowhere near the banking and speeds as Auto club speedway . advising camber settings is sillly, considering the varying amount of geometry of different cars suspention. Motion ratios,etc..(e.g. taking 2 degrees out of a mustang is different than taking 2 degrees out of a porsche 911, or struts vs coil overs etc)

yes, this is basic gas law. the point is, those that are seeing 180 to 200 tread temps, dont really know what the air temp is inside the tire. we dont need to .. all we need to know is the pressure change.
the fastest drivers out there in the very fastest cars are seeing around 10psi change. tread temps are in the 180 to 200 degrees regardless of ambient temps. (generally) if we started at 75 degrees, and ended up at over 220F, you would see about 10 psi of change. as a rule of thumb for each 10 degrees , its about 1psi. no one sees this kind of spread you mention 26psi to 40psi that i know of or ever heard of and im constantly polling folks in the paddock. we are all very close like that. like i said, most all the fast cars with the big power and weight in the 2800 to 3000lbs, start out at 22 to 24psi and end up at around 30psi.. i was only asking about the 14psi, because i have never seen or heard of that. I just got off the phone of one of the fastest guys in SCCA club in california... he runs slicks starts out at 19psi and ends up at 29psi. (this guy runs in the 1:27s at laguna and 1:39s at sears with a car weighing 3300lbs and near 1000 hp) The other top guys with 3000lb cars, National champions SCCA, NASA, or the equal to the fastest time in the same cars, run 22 psi to start and end up around 30psi... this is very common. you couldnt run those target pressures, of 30psi, if you had to start at 16psi on a Hoosier... that would be dangerous and tricky to get the tire warm without damaging it... so, i dont know how someone could see 14psi change, but thats why i asked and provided graphs to understand how its possible.

the question is really, how is one to measure tire internal air temps? is there a sensor in the rim that sits in the air and not getting a reading that is influenced by rim temps? curious. we are limited to surface temps with IR guns and penetrating temp gauges.

morsini

Aside from all the assumptions you've made about me, my level of education, racing experience and all that. You still haven't answered my question. When are you going to get the help you so desperately need? Are you off your meds again?

mark kibort

Actually i do. I've seen you drive.... You think you are a racer? you get confused by a simple Gas Law chart, so i suspect you dont have much engineering education.. you being a scientist, (My wife was a scientist/ genetic engineer and didnt know much about tire pressures either, so dont feel bad ) You would think that this would be fairly straight forward for you . But one thing for sure, you dont have manners! maybe you should consider a finishing school.

jdistefa

OMG is there a triple-popcorn emoji?

DTMiller

So true, I even got it on my mug.

Thundermoose

I don't care who you are, but that's funny right there.

Matt Romanowski

I get my measurements from TPMS. Most, if not all, motorsport grade TPMS transmit temp with the pressure. That is one of the great things about using them. As to the influence from rim temp, that depends on the sensor, type, insulation, car, etc. Sensors like the high end McLaren and BF1 system have pressure, temp, and internal tire IR sensors. The internal IR is pretty cool, but hard to make use of unless you have a tire deal and GREAT tire engineering support from a manufacturer. That level of help is only at the very highest levels where tire choice is wide open.

mark kibort

Now, that is some cool technology. i might guess it is measuring rim temperature, unless it has something that measures the air in the tire, like a filament, or some type of orifice that generates an air flow through it.. pressure sensors are pretty common now, as we all have them on newer street cars. Again, didnt mean to start a ruckus, but i thought it was interesting to see a 14psi pressure growth with someone's tires, and was curuious how internal temps were measured. so, Paul might this access to tire air temps? Again, its interesting, because ive polled a bunch of friends today regarding their starting and ending pressures and no one has come back with anything over 10psi. what have you seen?
I forgot to mention a clarification to your comment about never seeing a "140F " tracktemp.... I was talking about asphalt temps. (pointing the IR gun on the asphalt). usually when its about 100 to 110 degrees, you can see this kind of temps on the track. still , tire temps were (surface tread) were under 180-200F in the hot pit area.

anyway, here is a tire temp sensor, but its external. ive never heard of internal air temp sensor