Let's discuss: Tire temp tuning -- theory and example

[jfritz27]

I feel like maybe this site was linked in another thread somewhere before, but for track guys this is a super solid read:

https://nasaspeed.news/tech/wheels-t...the-racetrack/

It discusses theory behind what your tire temps can tell you and how you might use that information to fine tune your setup. The basic idea of "put heat where you need it" seems to be a nice way to sum it up conceptually, but applying in practice like everything else there will be nuances, assumptions, etc. This site also has a download link to a cool spreadsheet that does some of the basic calculations to get a sense of how your pressures are doing on an individual tire level with respect to camber, as well as averages side-to-side and front-to-back. It's really cool. The only inputs are optimal tire temp (I left at 180 -- and this is irrelevant for the deltas) and then your 3 pressures for each tire. With respect to on-tire temperature spread as an indicator of appropriate camber, the spreadsheet uses an ideal spread of 7deg, but acknowledges this may need to vary.

Below is a link to a screen grab of this sheet filled in with some temps I took on one of my days last year, followed by some of the basic take-aways from my interpretation, then I threw out some questions/points for discussion. Was hoping we could be use this as a springboard to talk about basic approaches to chassis tuning based on tire temps and how people might approach it, and any future related questions on tire temps could be raised here.

My setup:
- ZCP with B16 Damptronic suspension & CS EDC calibration
- Stock sways
- FTA monoballs
- NT01 275/305
- Alignment: Front camber -3, toe out 0.25 deg per side (I think this is right); Rear camber -1.9, toe in 0.17 per side

Track: NJMP Lightning. CW track (so left side is the outside), with 2 left-handers

Link to spreadsheet image: https://drive.google.com/file/d/1Qxl...ew?usp=sharing

My observations:
- Outside tire temps are pretty equal across tread, suggesting more negative camber may be needed there
- A very large spread (20-30 deg) on the inside tires
- Delta: Left side hotter than right (by average of ~+ 15 deg)
- Delta: Rear is slightly hotter than front (about 5 degrees)

Questions/discussion:
1. Should i be worried about the on-tire spread for the inside tires? With regular axle rotation, the inside-outside wear on the tire seemed fairly good, so maybe this spread doesn't better in practice. Otherwise, in theory LESS negative camber might be the fix?
2. Side-to-side delta: I would think on a CW track you would expect that the outside should be somewhat hotter, but is there a rough guide as to how much of a difference is appropriate? Perhaps on a fully sorted track car with top-tier suspension bits you would have nearly equal temps
3. Front-to-rear delta: In my case, this difference seems pretty nominal. Thoughts on this?

Ultimately, these numbers may be acceptable within the context of the limitations of my current setup with the B16. But I figured would be a good way to stimulate some discussion on the topic.

Go!

[D_SheerDrivingPleasure]

Props to you for going this extra step. I've considered measuring temps but if you want accruate data you can't take a cool down lap. Without one, my brakes will spontaneously combust.

When I cash in my bit coins I'll hire track support to measure temps in pit lane.

[robbo mcs]

Originally Posted by jfritz27

I feel like maybe this site was linked in another thread somewhere before, but for track guys this is a super solid read:

https://nasaspeed.news/tech/wheels-t...the-racetrack/

It discusses theory behind what your tire temps can tell you and how you might use that information to fine tune your setup. The basic idea of "put heat where you need it" seems to be a nice way to sum it up conceptually, but applying in practice like everything else there will be nuances, assumptions, etc. This site also has a download link to a cool spreadsheet that does some of the basic calculations to get a sense of how your pressures are doing on an individual tire level with respect to camber, as well as averages side-to-side and front-to-back. It's really cool. The only inputs are optimal tire temp (I left at 180 -- and this is irrelevant for the deltas) and then your 3 pressures for each tire. With respect to on-tire temperature spread as an indicator of appropriate camber, the spreadsheet uses an ideal spread of 7deg, but acknowledges this may need to vary.

Below is a link to a screen grab of this sheet filled in with some temps I took on one of my days last year, followed by some of the basic take-aways from my interpretation, then I threw out some questions/points for discussion. Was hoping we could be use this as a springboard to talk about basic approaches to chassis tuning based on tire temps and how people might approach it, and any future related questions on tire temps could be raised here.

My setup:
- ZCP with B16 Damptronic suspension & CS EDC calibration
- Stock sways
- FTA monoballs
- NT01 275/305
- Alignment: Front camber -3, toe out 0.25 deg per side (I think this is right); Rear camber -1.9, toe in 0.17 per side

Track: NJMP Lightning. CW track (so left side is the outside), with 2 left-handers

Link to spreadsheet image: https://drive.google.com/file/d/1Qxl...ew?usp=sharing

My observations:
- Outside tire temps are pretty equal across tread, suggesting more negative camber may be needed there
- A very large spread (20-30 deg) on the inside tires
- Delta: Left side hotter than right (by average of ~+ 15 deg)
- Delta: Rear is slightly hotter than front (about 5 degrees)

Questions/discussion:
1. Should i be worried about the on-tire spread for the inside tires? With regular axle rotation, the inside-outside wear on the tire seemed fairly good, so maybe this spread doesn't better in practice. Otherwise, in theory LESS negative camber might be the fix?
2. Side-to-side delta: I would think on a CW track you would expect that the outside should be somewhat hotter, but is there a rough guide as to how much of a difference is appropriate? Perhaps on a fully sorted track car with top-tier suspension bits you would have nearly equal temps
3. Front-to-rear delta: In my case, this difference seems pretty nominal. Thoughts on this?

Ultimately, these numbers may be acceptable within the context of the limitations of my current setup with the B16. But I figured would be a good way to stimulate some discussion on the topic.

Go!

Side to side delta really depends on the track. However, assuming you are not doing a figure of 8 type circuit, then the predominant outer side of the car will always be much more important. You should be tuning the suspension to get the outside side of the car as good as possible, the inside side is more a passenger. So on a clockwise circuit, the left side of the car is the most important.

Front to rear delta depends on so many things, and is track dependent to some degree. However, in a RWD car, the front is heated up by a combination of braking forces and cornering forces, the proportion of which will depend on the track. Rear is more complicated, mix of power/traction, cornering and a lesser degree of braking. So for both, and also the relative F/R variation will change with fast power circuits vs short tight etc.

Also worth remembering with dynamic forces the alignment will alter slightly under braking vs cornering, eg dynamic camber changes. Suspension changes will alter it all as well.

Also, very important to remember that the aim is to get faster, not to ger a perfect spread of temps and tyre wear. The two are related, but not necessarily the same

[jfritz27]

Originally Posted by D_SheerDrivingPleasure

Props to you for going this extra step. I've considered measuring temps but if you want accruate data you can't take a cool down lap. Without one, my brakes will spontaneously combust.

When I cash in my bit coins I'll hire track support to measure temps in pit lane.

Hah, yeah... Definitely many caveats to the weekend warrior's approach, but I think still potentially useful to identify more glaring issues. The data-driven aspect of it tickles a certain part of the brain too. I'm going to try to do it consistently this season for fun. Also will be trying out the CR-1 so figured it might help tweak pressures a bit or at least ensure I'm not way off.

[jfritz27]

Originally Posted by robbo mcs

Also, very important to remember that the aim is to get faster, not to ger a perfect spread of temps and tyre wear. The two are related, but not necessarily the same

Very true -- that is the ultimate goal!

Thanks for chiming in

[FaRKle!]

Originally Posted by D_SheerDrivingPleasure

I've considered measuring temps but if you want accruate data you can't take a cool down lap.

This. A lot of tire temp/pressure tuning assumes you can take temps right after a corner, which clashes with most of reality. Even BMW in their own racing technical manuals (the kind you get when you buy a factory GT3/4/CS-Racing car) talks about them more in terms of when you're more commonly able to measure temperatures.

One of the biggest surprises from the BMW manual was that on the M2 CS-Racing they recommended a pretty significant temperature gradient of like 40 deg across the tire (20deg outside to mid, 20 deg from mid to inside). Now, the actual gradient amount will be camber dependent, but I agree with the "adjust to achieve an even gradient across the tire" approach as a start to recording and tuning.

[D_SheerDrivingPleasure]

The idea behind the cup 2 connects is intriguing but it seems gimmicky to an old guy like me and the last thing I need in my life is another beeping/blinking app sending me notifications.

Has anyone tired them? Could it replace the pyrometer?