Reading tire temps....
05-11-2007, 10:15 AM
#1
Rennlist Member
Thread Starter
Reading tire temps....
Last weekend I took some tire temps at the Glen. I was running Nitto NT-01s for the first time, 245s and 315s. Nitto says they like to be between 160° F. and 220° F. In earlier sessions I had stabilized the hot pressures at 38 psi for all four corners. Ambient temperature was in the mid 60s. Here is what I got for three measurements:
Imagine looking down on the car from the top. The four tires are:
LF | RF
LR | RR
Here are the temperatures, arranged just as if you were looking at the tires from above, with outside | center| inside on the left and inside | center|outside on the right:
#1
154 154 168 | 150 134 118
185 193 188 | 197 188 151
#2
146 152 167 | 167 141 117
176 191 210 | 199 170 151
#3
132 152 169 | 168 141 106
166 189 206 | 197 162 141
Here are some more temps:
What do you suggest for pressures (I had left them all at 38 psi hot) and alignment?
My front camber is -2.6° with 0 toe and my rear camber is -2.4° with 1/8" toe.
Imagine looking down on the car from the top. The four tires are:
LF | RF
LR | RR
Here are the temperatures, arranged just as if you were looking at the tires from above, with outside | center| inside on the left and inside | center|outside on the right:
#1
154 154 168 | 150 134 118
185 193 188 | 197 188 151
#2
146 152 167 | 167 141 117
176 191 210 | 199 170 151
#3
132 152 169 | 168 141 106
166 189 206 | 197 162 141
Here are some more temps:
What do you suggest for pressures (I had left them all at 38 psi hot) and alignment?
My front camber is -2.6° with 0 toe and my rear camber is -2.4° with 1/8" toe.
05-11-2007, 11:04 AM
#2
Addict
Rennlist Member
Rennlist Member
I'm sure more experienced/capable tire pros will weigh in here, but some baseline thoughts - looks like you're sliding the rear end around a lot more than the front? It should come as no surprise that I don't know much about 911-specific setup, but it surprises me to see so much temp difference front to rear...
I'll pass on anything further, other than to note that it seems like you've got more camber than necessary... but again, I'll let the experts discuss that...
I'll pass on anything further, other than to note that it seems like you've got more camber than necessary... but again, I'll let the experts discuss that...
05-11-2007, 11:21 AM
#3
Burning Brakes
You're running too much neg. camber, and now you know that your current "WGI setup" will be happier with a little less camber on the right side of the car (not surprising for WGI).
05-11-2007, 11:27 AM
#4
Rennlist Member
Thread Starter
Originally Posted by Professor Helmüt Tester
You're running too much neg. camber, and now you know that your current "WGI setup" will be happier with a little less camber on the right side of the car (not surprising for WGI).
I'll leave it balanced left to right as I will not drive only at WGI.
05-11-2007, 11:35 AM
#5
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Based upon the left (loaded) side temps, I think that the front is fine, though you may want to go down to -2.0° in the back. You might also want to drop your pressures a few lbs, as the center temps are running higher than the outside. Also, how are you taking the temps; right off of a hot lap, or at the end of the session? Remember that the long slow cooldown lap make the outside edges cool faster than the inside.
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Larry Herman
2016 Ford Transit Connect Titanium LWB
2018 Tesla Model 3 - Electricity can be fun!
Retired Club Racer & National PCA Instructor
Past Flames:
1994 RS America Club Racer
2004 GT3 Track Car
1984 911 Carrera Club Racer
1974 914/4 2.0 Track Car
CLICK HERE to see some of my ancient racing videos.
05-11-2007, 11:43 AM
#6
Race Car
154 154 168 | 150 134 118
Avg 161 (+7) | 134 (0)
185 193 188 | 197 188 151
avg 186.5 (-6.5) | 174 (-14)
========================
#2
146 152 167 | 167 141 117
Avg 156.5 (+4.5) | 142 (+1)
176 191 210 | 199 170 151
Avg 192 (+1) | 175 (+5)
===========================================
#3
132 152 169 | 168 141 106
Avg 150.5 (-1.5) | 137 (-4)
166 189 206 | 197 162 141
avg 186 (-3) | 169 (+7)
does this help....
05-11-2007, 11:57 AM
#7
Burning Brakes
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A little less pressure in the back is needed.
Possibly too much camber in the back.
What is your level of experience? What lap times?
I used to have situations when at first it shows that I have too much camber and then I up the speed through the corners and the temps even out.
Possibly too much camber in the back.
What is your level of experience? What lap times?
I used to have situations when at first it shows that I have too much camber and then I up the speed through the corners and the temps even out.
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05-11-2007, 12:06 PM
#8
this may be a case where a slightly smaller front tire is faster.
I agree with amaist. If you are at a point where speeds will still come up significantly then you may end up with really good numbers.
I agree with amaist. If you are at a point where speeds will still come up significantly then you may end up with really good numbers.
05-11-2007, 12:13 PM
#9
Rennlist Member
Thread Starter
Lots of good thoughts, thanks.
These temps were taken right off a hot lap. It took a few moments to get good with the temp probe, but it was not after a cool down lap.
I can easily play with my tire pressures, and lowering them should help and I can monitor that.
I have some video of my laps, but have not determined lap times from them. That's an important point I have not addressed. I'm in my 3d season of DE driving and I am not what I would consider fast. Of course I'm not sure I'm going to be much faster any time soon. I do not have a lap timer.
I hope to get to Cups and Saucers next week and I can see what pressure changes do for me. I can also hope to get some help of others in taking multiple temperature checks in one session. I was a bit on my own last weekend.
These temps were taken right off a hot lap. It took a few moments to get good with the temp probe, but it was not after a cool down lap.
I can easily play with my tire pressures, and lowering them should help and I can monitor that.
I have some video of my laps, but have not determined lap times from them. That's an important point I have not addressed. I'm in my 3d season of DE driving and I am not what I would consider fast. Of course I'm not sure I'm going to be much faster any time soon. I do not have a lap timer.
I hope to get to Cups and Saucers next week and I can see what pressure changes do for me. I can also hope to get some help of others in taking multiple temperature checks in one session. I was a bit on my own last weekend.
05-11-2007, 12:24 PM
#10
Still plays with cars.
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Member
Originally Posted by Phokaioglaukos
Last weekend I took some tire temps at the Glen. I was running Nitto NT-01s for the first time, 245s and 315s. Nitto says they like to be between 160° F. and 220° F. In earlier sessions I had stabilized the hot pressures at 38 psi for all four corners. Ambient temperature was in the mid 60s. Here is what I got for three measurements:
Imagine looking down on the car from the top. The four tires are:
LF | RF
LR | RR
Here are the temperatures, arranged just as if you were looking at the tires from above, with outside | center| inside on the left and inside | center|outside on the right:
#1
154 154 168 good | 150 134 118 add air
185 193 188 good | 197 188 151 add air
#2
146 152 167 Less air | 167 141 117 add air
176 191 210 less air | 199 170 151 add air
#3
132 152 169 less air | 168 141 106 add air
166 189 206 less air | 197 162 141 add air
Here are some more temps:
What do you suggest for pressures (I had left them all at 38 psi hot) and alignment?
My front camber is -2.6° with 0 toe and my rear camber is -2.4° with 1/8" toe.
Imagine looking down on the car from the top. The four tires are:
LF | RF
LR | RR
Here are the temperatures, arranged just as if you were looking at the tires from above, with outside | center| inside on the left and inside | center|outside on the right:
#1
154 154 168 good | 150 134 118 add air
185 193 188 good | 197 188 151 add air
#2
146 152 167 Less air | 167 141 117 add air
176 191 210 less air | 199 170 151 add air
#3
132 152 169 less air | 168 141 106 add air
166 189 206 less air | 197 162 141 add air
Here are some more temps:
What do you suggest for pressures (I had left them all at 38 psi hot) and alignment?
My front camber is -2.6° with 0 toe and my rear camber is -2.4° with 1/8" toe.
Were you able to measure with the tires hot or only after a cool down lap? I am suspicious about the low inside edge temps on the RR.
Toe in tends to make the outside a little hotter especially if you measure right after a longish straight section with corners taken slowly on a cool down. My guess is that you will find 34-36 lbs a better hot pressure. How was the handling - that is also an important piece of the puzzle? If you can't get the temps more even in the rear, you might want to think about tweaking the sway bars if they are adjustable.
Best,
05-11-2007, 01:36 PM
#11
Rennlist Member
Thread Starter
Originally Posted by Bob Rouleau
How was the handling - that is also an important piece of the puzzle? If you can't get the temps more even in the rear, you might want to think about tweaking the sway bars if they are adjustable.
I'll play with tire pressures for the next event and then think again about camber changes. I'll also figure out some lap times from my video camera this evening and let you all know just how slow I am!
05-11-2007, 04:41 PM
#12
Still plays with cars.
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Chris - my 996GT3 went well with acceptably even temps with 2.5 neg front and 5 mins toe in per wheel and neg 2.4 in back with 17 mins toe in per wheel. Front bar in stock position and the rear one hole softer than stock. Michelin Cups in stock sizes. I was thinking one hole stiffer based on your temps but I would not change anything until after you adjust pressures to try and even out the temps across the surface. Yoou will never get them perefectly even but the deviation from the average should be closer than what you have now. I understand not wanting to have a Glen specific set-up and I don't blame you.
I also attribute the greasy feeling near the end of the session to your tire pressures rising above the optimal level. Sadly I have no experience with the Nitto tires ...
Best,
I also attribute the greasy feeling near the end of the session to your tire pressures rising above the optimal level. Sadly I have no experience with the Nitto tires ...
Best,
05-11-2007, 10:54 PM
#14
Race Car
Originally Posted by Phokaioglaukos
Last weekend I took some tire temps at the Glen. I was running Nitto NT-01s for the first time, 245s and 315s. Nitto says they like to be between 160° F. and 220° F. In earlier sessions I had stabilized the hot pressures at 38 psi for all four corners. Ambient temperature was in the mid 60s. Here is what I got for three measurements:
Imagine looking down on the car from the top. The four tires are:
LF | RF
LR | RR
Here are the temperatures, arranged just as if you were looking at the tires from above, with outside | center| inside on the left and inside | center|outside on the right:
#1
154 154 168 | 150 134 118
185 193 188 | 197 188 151
#2
146 152 167 | 167 141 117
176 191 210 | 199 170 151
#3
132 152 169 | 168 141 106
166 189 206 | 197 162 141
Here are some more temps:
What do you suggest for pressures (I had left them all at 38 psi hot) and alignment?
My front camber is -2.6° with 0 toe and my rear camber is -2.4° with 1/8" toe.
Imagine looking down on the car from the top. The four tires are:
LF | RF
LR | RR
Here are the temperatures, arranged just as if you were looking at the tires from above, with outside | center| inside on the left and inside | center|outside on the right:
#1
154 154 168 | 150 134 118
185 193 188 | 197 188 151
#2
146 152 167 | 167 141 117
176 191 210 | 199 170 151
#3
132 152 169 | 168 141 106
166 189 206 | 197 162 141
Here are some more temps:
What do you suggest for pressures (I had left them all at 38 psi hot) and alignment?
My front camber is -2.6° with 0 toe and my rear camber is -2.4° with 1/8" toe.
05-12-2007, 12:41 AM
#15
Formula One Spin Doctor
Rennlist Member
Rennlist Member
Originally Posted by 924RACR
I'm sure more experienced/capable tire pros will weigh in here, but some baseline thoughts - looks like you're sliding the rear end around a lot more than the front? It should come as no surprise that I don't know much about 911-specific setup, but it surprises me to see so much temp difference front to rear...
I'll pass on anything further, other than to note that it seems like you've got more camber than necessary... but again, I'll let the experts discuss that...
I'll pass on anything further, other than to note that it seems like you've got more camber than necessary... but again, I'll let the experts discuss that...