Got a tire pyrometer - comments appreciated

[turbogrill]

Hi,

 

Finally got a fancy tire pyrometer (longacre).

 

Temps are taken very quickly after driving in Texas heat.  The probe only sticks out 1/16" or so, isn't it supposed to go deeper into the tires? I would expect the temps to be higher.

 

Tire is a 195" Direzza Z3 on a NA Miata with softish springs.

 

Track has a lot of right turns, I started measuring right front->right rear->left rear->left front.

 

 

 

Left Front: Looks good?

Right left: Too much pressure? Temps are low. Maybe stiffen swaybar?  But right rear looks not too bad

Right Front: Too much camber?

Right rear: Too much camber?

 

Could you tell anything about driver style?

 

 

 

 

 

 

 

[atxe30]

thanks for the hook-up with that today! I like the one you got better than mine. I'm sending mine back and getting one of those!!!

[mender]

4 hours ago, turbogrill said:

Hi,

 

Finally got a fancy tire pyrometer (longacre).

 

Temps are taken very quickly after driving in Texas heat.  The probe only sticks out 1/16" or so, isn't it supposed to go deeper into the tires? I would expect the temps to be higher.

 

Tire is a 195" Direzza Z3 on a NA Miata with softish springs.

 

Track has a lot of right turns, I started measuring right front->right rear->left rear->left front.

 

 

 

Left Front: Looks good?

Right left: Too much pressure? Temps are low. Maybe stiffen swaybar?  But right rear looks not too bad

Right Front: Too much camber?

Right rear: Too much camber?

 

Could you tell anything about driver style?

He likes to spin the right rear out of the slow right corners to try to make up for overshooting the turn in point. 

 

Just kidding; it's hard to say that the temp spreads are caused by driving style unless you have different temps from another driver at the same track.

 

Need more input!

1. Track map or at least description of the turns (high/low speed, banking, elevation changes, etc)

2. How the car is handling, any quirks, ie. understeers to the right and oversteers to the left

3. Corner weights 

4. Age of tires (all the same vs 5 hours on one and 15 hours on another)

 

Right now:

LF: only an 8 degree spread outside to inside, so likely need more negative camber and a little less pressure.

RF: 30 degree spread so too much negative camber, a little more pressure.

LR: 10 degree spread so more negative camber needed, need a little less pressure.

RR: 15 degree spread so probably about right, same with pressure.

 

Just a guess but you might have some cross weight happening, LF and RR are hotter than the RF and LR.

Edited September 9, 2021 by mender

[MichaelPal]

My thought process (assuming tires have reached steady state - peak temps): 

 

LF: no touchy

RF: drop 0.5psi (but really might end up at 1.0psi drop)

 

LR: no touchy 

RR: no touchy 

 

 

This statement varies track track to track ambient to ambient. 

 

In all honesty, I am still learning what’s best. But the above would be my approach presented with that data. 

 

(Also what longacre gauge are you using?) 

Edited September 9, 2021 by MichaelPal

[turbogrill]

7 minutes ago, mender said:

He likes to spin the right rear out of the slow right corners to try to make up for overshooting the turn in point. 

 

Just kidding; it's hard to say that the temp spreads are caused by driving style unless you have different temps from another driver at the same track.

 

Need more input!

1. Track map or at least description of the turns (high/low speed, banking, elevation changes, etc)

2. How the car is handling, any quirks, ie. understeers to the right and oversteers to the left

3. Corner weights 

4. Age of tires (all the same vs 5 hours on one and 15 hours on another)

 

1.

Harris Hill, 

t1 = 81mph

t2,t3= 63mph,

t4 = 45-50mph

t5 = 56mph

t6 = 80mph

t7 = 50mph

t8 = 72mpp

t9 = 80mph

t10 = 45

t11 = 72mph

 

2.

It's a miata so pretty neutral. But on lowering springs and some cheap shocks. 

 

3.

No clue

 

4.

Almost new! Maybe 2-3 hours

 

I redid the measurements a few times and it's very important that the probe is being inserted at the same spot everytime. 

[turbogrill]

1 minute ago, MichaelPal said:

My thought process (assuming tires have reached steady state - peak temps): 

 

LF: no touchy

RF: drop 0.5psi (but really might end up at 1.0psi drop)

 

LR: no touchy 

RR: no touchy 

 

 

This statement varies track track to track ambient to ambient. 

 

In all honesty, I am still learning what’s best. But the above would be approach presented with that data. 

 

(Also what longacre gauge are you using?) 

 

My club mates running very similar cars are running a little higher. Rear left was something like 33psi hot. It's a little confusing.

Got the fancy Long acre that is tire pressure gauge and pyrometer all in one. 

 

 

[MichaelPal]

12 minutes ago, turbogrill said:

 

My club mates running very similar cars are running a little higher. Rear left was something like 33psi hot. It's a little confusing.

Got the fancy Long acre that is tire pressure gauge and pyrometer all in one. 

 

 

 

Am I blind or where is the pressure? 

 

For me, pressure can be whatever it wants in order to get an ideal temp spread. Then I work from there. 

 

Did your buddy take temps temps as well? Ultimate lap time is one thing, good temp distribution for the long term is another balancing act. 

Edited September 10, 2021 by MichaelPal

[turbogrill]

40 minutes ago, MichaelPal said:

 

Am I blind or where is the pressure? 

 

For me, pressure can be whatever it wants in order to get an ideal temp spread. Then I work from there. 

 

Did your buddy take temps temps as well? Ultimate lap time is one thing, good temp distribution for the long term is another balancing act. 

 

Hi,

 

There is no pressure on the image, I should have! Next time

 

I don't think my buddies took any temps, just based on feel. And they are 1.5s faster then me on a 1.35s lap

 

Most likely better driving...

[Grant]

Probe lengths are often adjustable if you unscrew the tip.

 

The 10-20F spread rule of thumb is, IME, usually BS. We went from a 15-20F spread in front to 25-30F and picked up a lot of front grip and more even tire wear. Granted a lot of this depends on braking. Lots of slip (ABS) will heat up the insides a lot more, especially in the front. We found the rear seems to like less spread, probably for this reason.

 

As you found out, probe placement is super important. This is another reason why I don't think the rules of thumb tell you much. I've been meaning to make something that lays across the tire so I put the probe in the exact same spot each time.

 

I've run a spread of tires pressures, 30 to 40 psi in 2 psi increments (on a heavier car), taking daq and temps each stop. There's not much time in optimizing pressures. The car will be sharper with higher pressures but develop a bit less grip. With lower pressures it'll feel like crap, but if you can drive around the slower transitions it doesn't hurt you too much. On a stiffly sprung car pressures can be used to fine-tune balance, since the tire spring rate has more influence on the total wheel rate when the springs are stiffer.

 

It's up to you how to interpret right-side data on a track with mostly rights. Sure it looks like you need less camber, but those few left turns might be really important? Or not.

 

If you're 1.5s behind I wouldn't worry about fine-tuning camber and tire pressures.

Edited September 10, 2021 by Grant

[thewheelerZ]

If you go back and measure your right front as a 5th measurement you will get a base for how much that tire has cooled in the time it took to measure the others. Could help for data. 
 

in the temp differential do you want and even spread across the tire? I.e. if you plotted them up it would be a straight-ish line? Would that give an indication of how pressures are working? 

[MR2 Biohazard]

17 hours ago, turbogrill said:

Hi,

 

Finally got a fancy tire pyrometer (longacre).

 

Temps are taken very quickly after driving in Texas heat.  The probe only sticks out 1/16" or so, isn't it supposed to go deeper into the tires? I would expect the temps to be higher.

 

Tire is a 195" Direzza Z3 on a NA Miata with softish springs.

 

Track has a lot of right turns, I started measuring right front->right rear->left rear->left front.

 

 

 

Left Front: Looks good?

Right left: Too much pressure? Temps are low. Maybe stiffen swaybar?  But right rear looks not too bad

Right Front: Too much camber?

Right rear: Too much camber?

 

Could you tell anything about driver style?

 

 

 

 

 

 

 

Ideal that I have found is about 15-25 across the tire with the inside being hotter as that should be contacting the road for braking in a straight line more and also used in the corners.

 

 

Left front- Add camber and loose pressure.

Right front- less camber- maybe more pressure- depends no how the camber affects it. I would say change one thing at a time.

Left rear- Needs more camber and less pressure

Right rear- looks good.

 

A big point here is do not worry about a tire pressure being a certain number. Adjust tire pressures to get the correct temperature. It does not matter if it is 28 or 38, as long as the tire pressure and alignment all work together to get the right temperature and then all will be great.

 

Write it all down and save it for different tracks. Eventually it will become second nature and the pyrometer is not used all that often, more to verify if all is still good.

[turbogrill]

54 minutes ago, MR2 Biohazard said:

Ideal that I have found is about 15-25 across the tire with the inside being hotter as that should be contacting the road for braking in a straight line more and also used in the corners.

 

 

Left front- Add camber and loose pressure.

Right front- less camber- maybe more pressure- depends no how the camber affects it. I would say change one thing at a time.

Left rear- Needs more camber and less pressure

Right rear- looks good.

 

A big point here is do not worry about a tire pressure being a certain number. Adjust tire pressures to get the correct temperature. It does not matter if it is 28 or 38, as long as the tire pressure and alignment all work together to get the right temperature and then all will be great.

 

Write it all down and save it for different tracks. Eventually it will become second nature and the pyrometer is not used all that often, more to verify if all is still good.

 

The reason you want to loose pressure on left side is to get a steeper gradient?

 

 

[MR2 Biohazard]

5 minutes ago, turbogrill said:

 

The reason you want to loose pressure on left side is to get a steeper gradient?

 

 

yes. You want like 10-20 accross.

 

example

140-150-150

pressure too high

 

140-160-150

pressure too high

 

140-130-150 pressure too low

 

140-150-160  even from step to step, sooo yummy

 

Also, you might find your car and tires size likes 12 degrees across 140-146-152

Or it might like 18, or 24, or 9. That just depends on the tires size, how hard the car is on tires, ect. You need to find what is best for your setup, though being even across is best.

 

The easit way I found is camber will do the outside and inside numbers and get those right first. Then fine tune middle to make it even. I usually use 24-27 psi cold pressure to start with and go from there. Then adjust and after it is right and good and cools down you know what your cold pressure should be at Temperature X. Then adjust as needed. Meaning if we start the day at 40F I might drop the pressure a degree to two starting and go from there if we use 70F as a baseline.

[Grant]

He needs to get up to speed first. The temp data gathered when 1.5s behind is going to be different than when the car is driven as fast as it can go. Though I guess more camber is in order either way.

Edited September 10, 2021 by Grant

[Bandit]

That right front has me thinking the car has a lot of roll.

[turbogrill]

7 hours ago, Bandit said:

That right front has me thinking the car has a lot of roll.

It has!

 

Got the stiffest springs I could find that is not coilovers. 

 

Got a stiff sway but understeers too much when too stiff.

Might be possible to drill the rear sway, but would require shortening the end links. Didn't want to do that at the moment.

[mender]

This may be of interest:

https://speedsecrets.com/Tires-for-Drivers/?ck_subscriber_id=826626215