what does this tire temp data show me? (a/x app)
08-13-2007, 10:50 AM
#1
Burning Brakes
Thread Starter
what does this tire temp data show me? (a/x app)
Got a new probe type pyrometer and used it yesterday for the 1st time. Gathered inside/outside edge temps after each run on all 4 corners and gathered the following:
all temps shown in *F, red pairs are < 2* diff, blues are > 3*
tires are Kuhmo Victoracers, 315/35/17 on all 4 corners
A couple specific questions:
1) can I say in general that my alignment and pressure setup for the LF & RR are correct for those conditions because the temp diff was minimal? Is minimal temp diff an indicator for that?
2) when using tire temps from outside edge and inside edge what is the "minimal" temperature diff that indicates your setup is right?
all temps shown in *F, red pairs are < 2* diff, blues are > 3*
tires are Kuhmo Victoracers, 315/35/17 on all 4 corners
A couple specific questions:
1) can I say in general that my alignment and pressure setup for the LF & RR are correct for those conditions because the temp diff was minimal? Is minimal temp diff an indicator for that?
2) when using tire temps from outside edge and inside edge what is the "minimal" temperature diff that indicates your setup is right?
Last edited by astock165; 08-13-2007 at 10:52 AM.
08-13-2007, 11:28 AM
#2
Safety Car
Assuming these were HPDE sessions it looks like your camber is set about where you want it. But, without a center of tread temp it's impossible to determine whether your tire pressure is right or not. A very general rule of thumb is to add or subtract 1 lb of air pressure for every 5 degrees of temp difference. Inside and outside you're looking fine, next time take some center of tread measurements too.
08-13-2007, 11:59 AM
#3
Those look good, 3-5 degrees across the tread is a reasonable spread from a camber standpoint.
If you are measuring right after pulling off a skidpad, I'd look for a tighter temperature difference. If you pulled back into your grid spot after a run, usually the outside edge starts cooling off by the time you get to check.
Based on the last run temps, where your outside edges got hotter - did you push the car a little harder? I would consider adding another 1/4 degree of camber to compensate. But the gains are getting small at that point.
If you are measuring right after pulling off a skidpad, I'd look for a tighter temperature difference. If you pulled back into your grid spot after a run, usually the outside edge starts cooling off by the time you get to check.
Based on the last run temps, where your outside edges got hotter - did you push the car a little harder? I would consider adding another 1/4 degree of camber to compensate. But the gains are getting small at that point.
08-13-2007, 12:46 PM
#4
Burning Brakes
Thread Starter
But, without a center of tread temp it's impossible to determine whether your tire pressure is right or not. A very general rule of thumb is to add or subtract 1 lb of air pressure for every 5 degrees of temp difference. Inside and outside you're looking fine, next time take some center of tread measurements too.
08-13-2007, 12:53 PM
#5
Race Director
those temps really aren't high enough to have much meaning imho. That is so close to ambient/track temp that it is very hard to differentiate true friction heat and background noise.
For setting up and auto-x car, you almost need a skidpad!
For setting up and auto-x car, you almost need a skidpad!
08-13-2007, 12:59 PM
#6
Safety Car
Member Since: May 2006
Location: Northern Virginia
Posts: 3,799
Likes: 0
Received 1 Like
on
1 Post
St. Jude Donor '08
No expert, but a couple of thoughts.
I would be comparing fronts to fronts and rears to rears. There seems to be a big temp diference between the rears, although there also seems to be a significant difference in the front tire temps on some runs. Was the track predominantly left or right turns, or pretty much equal?
Your tire temps seem pretty low. What is the operating temp range for this tire? When did you take temps? If you are significantly below operating temp it suggest that you are not driving the car hard enough. Tires can cool very quickly.
The temps on the individual tires seem to be pretty consistent suggesting the tires are properly inflated and suspension settings are good.
I would be comparing fronts to fronts and rears to rears. There seems to be a big temp diference between the rears, although there also seems to be a significant difference in the front tire temps on some runs. Was the track predominantly left or right turns, or pretty much equal?
Your tire temps seem pretty low. What is the operating temp range for this tire? When did you take temps? If you are significantly below operating temp it suggest that you are not driving the car hard enough. Tires can cool very quickly.
The temps on the individual tires seem to be pretty consistent suggesting the tires are properly inflated and suspension settings are good.
08-13-2007, 02:03 PM
#7
Tech Contributor
Member Since: Oct 1999
Location: Charlotte, NC (formerly Endicott, NY)
Posts: 40,138
Received 8,964 Likes
on
5,350 Posts
It seems to me you would get a better picture by including the center temp of each tire. That would help in determining alignment settings and pressure settings. The V700 is at its most efficient temperature from 160 to 200 degrees which will never occur during a normal autocross.
Bill
Bill
08-13-2007, 02:34 PM
#8
Melting Slicks
Without a MIDDLE temp you don't know if you are underinflated or overinflated.... Without a middle temp the data isn't totally worthless, but just about.. If you just rely on the inside and outside temps, you may have a lot more pressure in the tire than you want, and that will result in a stiffer tire, which means less rollover, which means the camber setting may or may not be right...... Well, you get the idea.... Take middle temps too and then see where you are.
08-13-2007, 02:41 PM
#9
Burning Brakes
Thread Starter
After the run and when I got back to my paddock as there was no grid area. Admittedly it was a few hundred yards away and I had to get out my harness & helmet and then start, could be as much as 3-5 minutes.
Someone else had mentioned that as well, I will certainly do it next time.