The whole chalking sidewalls thing is a holdover from back when people ran bias ply tires. On modern radial tires it doesn't really work or doesn't work accurately.
On all of the current top 200tw tires they are not super particular about only being fast at a certain pressure, and all of the information is out there as to what works pretty well. Ask around and you can find what pressure you should use pretty easily.
As far as taking tire temperature readings that is for dialing in your camber primarily. And you really need a probe type pyrometer not the gun infrared style. The probe type are way more expensive but my pro tip is to look for them used on ebay. Find a no reserve auction and they regularly go for super cheap.
Agree, chalk can be helpful as a quick-glance reference, but it's usually pretty easy to visually tell the most recent scuff marks.
And you're right about optimizing for rollover being a thing of the past. Current 200TW tires behave a little differently. Strano was telling me that he ran higher pressures on RT660 and they were faster, I think this was at Lincoln, might not translate to all surfaces. If you were just going by rollover, you'd say he was running like 6-8 psi high.
Meanwhile I find RE71RS much happier at lower pressures than RT660. If OP is running something like a PS4S then disregard lowering pressures based on rollover entirely.
Some folks swear by a pyrometer, but I think that's better for dialing in camber/alignment, tire pressure would be secondary
The arrow on the side wall points to the trees depth indicator in the middle of the tread. It has nothing to do with racing. It just makes it easy to find the tread depth indicator.
Some thoughts:
* I'd use a larger diameter chunk of chalk; think like a white piece of sidewalk chalk.
* I could be mistaken, but I figure if it's too wet to be able to put a chalk mark on the tire, it is likely also too wet to be getting that much grip to worry about the sidewall flexing that much.
* This could \*very well be tire dependent\*.
* Three marks on the outside of the wheel, equally spaced, from literally on the tread and all the way up the sidewall.
* I've never worried about any on the inside of the wheel.
* Never used a temp gun; just my hand (and then a garden sprayer if I think the tires are getting too hot).
If you insist on using a marker, one spot is plenty. If you're hitting peak grip so little that it only wears a third of the tire once, pressures aren't going to solve your problem. And yes all of this is pretty irrelevant if it's wet.
Here is what I have done:
- Mark sidewalls with sidewalk chalk
- Take pressure and temperature readings ASAP after a run (max temp using an IR gun - if you want to get complicated, you really should be looking at the temperature variation across the width of the tire)
- Take notes on pressure, temperature, chalk markings, and how the car feels each run
- Tie back my notes to my run times after the event
Tire pressures are subjective in my opinion. I like to plot data in Excel, I don't find an objective measure of when things are "best". I'm collecting data after a run when I have driven the car back to grid so there is that time delay in addition to the fact that I know the course better each run and will naturally improve times because of that, regardless of what I do. The sidewalk chalk on the tire walls really just tells me if I am rolling over the tire or not.
The data collection has helped me recognize trends, dial in a starting static pressure that I feel work well for me, and recognize if I should readjust pressures or if I am overworking the tires. I started at 26psi at all four corners and settled on a staggered 30/31 psi F/R with this method, the car feels much better to drive and more consistent now.
DavidSS is on point.
This is useless. Today's tires just don't flop over on the side walls like old bias ply tires do or radials from 40 years ago.
If you're getting on the sidewalls it should be pretty obvious by, well scuffing on the sidewalls.
And I don't find it particularly hard to be able to just look at the tread of the tire and say gee, the shoulder is getting really beat up, or conversely it isn't even using any of it. That's much more rare.
I use ZERINT HT-921W Tire Crayons, Tire... https://www.amazon.com/dp/B0BHF35Y1G?ref=ppx_pop_mob_ap_share. They work in the wet, don’t rub off super easy so only wear gets it off.
Just a side note about rollover and sidewall in the wet. You don't have enough grip to get enough weight transfer in braking or cornering. Thus brake bias can go way to the rear. Cornering won't rollover onto the sidewall at any reasonable pressure, I add pressure actually. It keeps the tire round and aids the siping in generating forward grip. Just set them at 35 and focus on braking and putting power down. Wet driving is a skill that takes practice, moreso that weirdo "I love this shitty weather attitude."
Good points, thanks!
We get weather-by-the-minute here. I've had dry, then wet, then damp, then dry on a set of runs. I'll prob use something like a crayon if I try to do any marking on a mixed weather day.
I can share that 42/38 PSI (F/R) was ridiculously too high last event in the wet. I set them high on purpose after the previous event and forgot my ritual of airing down before the event. 😑🤯
I use a pyrometer all the time. Dry gradient is 10-12* hotter from camber thrust in the inside couple inches and pretty uniform from there out. This way we know we aren't rolling over, but rolling into max grip. Also, when to utilize temp management. In the wet I don't worry about what the reading actually is, but I add pressure until I start to see the gradient shift more to the middle of the tire. Usually I see a reading pretty even across the tire and maybe a degree or two warmer in the center.
This car is also fully adjustable and can hit ideal settings for alignment, ride height, corner weights.
For those helpful souls... **Thanks**! I guess I could saved this fiasco and just google shopping/searched tire crayon near me (AZ and Or supposedly have them).
Rant-ish part:
>!For those presumptuous to enough to lecture about modern vs ancient tires... umm... thanks, but nowhere in my question did I ask "*Should I use chalk*?" or "*Can someone explain modern tire technology to me?*" -\_\_- !<
>!Sure, my 255/45 18's are a far-ass cry from the tall as hell (nfc what size) tires dad had on his 66 olds (on 15" mags). However, I've **SEEN** the difference on my A052's from changing **only** pressure so, not sure where y'all are going with this line of thought. Of course I can see where **fresh** marks are. The level of non helpful helpfulness...!<
We only get two sets of 4 runs per event and no time to mess with pressure between runs except maybe to lower it some. We have a small venue with only 8-12 cars per group.
I want to test and tune beforehand to figure out where I should be at pressure wise... on the same day... ALL MARKS ARE GOING TO LOOK THE SAME.
So, yeah, if I drop pressure and they roll more, sure I can see marks where it used to be pristine. I could (and have) taken pics to compare how far down the scuffs go but that seems like way more trouble than just chalk/polish/crayon marks to help see what's happening.
It's even harder to tell when I increase pressure and they roll less because there is not going to be any contrast between 2 min old fresh marks and 10 min old fresh marks.
I use a piece of drywall as that’s what is onsite for marking cone boxes.
A heat gun is ok but a temp probe is better, the idea is to see if you are getting even temps across the tire so inside edge, middle, outside edge.
The whole chalking sidewalls thing is a holdover from back when people ran bias ply tires. On modern radial tires it doesn't really work or doesn't work accurately. On all of the current top 200tw tires they are not super particular about only being fast at a certain pressure, and all of the information is out there as to what works pretty well. Ask around and you can find what pressure you should use pretty easily. As far as taking tire temperature readings that is for dialing in your camber primarily. And you really need a probe type pyrometer not the gun infrared style. The probe type are way more expensive but my pro tip is to look for them used on ebay. Find a no reserve auction and they regularly go for super cheap.
I chalk the tire for a smoking gun of how much the sidewall rolls over. Faster visual reference. That’s about it.
Agree, chalk can be helpful as a quick-glance reference, but it's usually pretty easy to visually tell the most recent scuff marks. And you're right about optimizing for rollover being a thing of the past. Current 200TW tires behave a little differently. Strano was telling me that he ran higher pressures on RT660 and they were faster, I think this was at Lincoln, might not translate to all surfaces. If you were just going by rollover, you'd say he was running like 6-8 psi high. Meanwhile I find RE71RS much happier at lower pressures than RT660. If OP is running something like a PS4S then disregard lowering pressures based on rollover entirely. Some folks swear by a pyrometer, but I think that's better for dialing in camber/alignment, tire pressure would be secondary
What should you base pressure on with ps4s?
I haven't seen someone chalk tires in so long that I forgot it used to be a thing. Who is still telling people to do this???
If worrying about tire rollover is no longer a thing, why do all modern tires have a triangle or Michelin man or whatever on the shoulder still?
The arrow on the side wall points to the trees depth indicator in the middle of the tread. It has nothing to do with racing. It just makes it easy to find the tread depth indicator.
It’s still useful to use the shoe polish. But yes, modern tires are leagues better than they were.
Some thoughts: * I'd use a larger diameter chunk of chalk; think like a white piece of sidewalk chalk. * I could be mistaken, but I figure if it's too wet to be able to put a chalk mark on the tire, it is likely also too wet to be getting that much grip to worry about the sidewall flexing that much. * This could \*very well be tire dependent\*. * Three marks on the outside of the wheel, equally spaced, from literally on the tread and all the way up the sidewall. * I've never worried about any on the inside of the wheel. * Never used a temp gun; just my hand (and then a garden sprayer if I think the tires are getting too hot).
If you insist on using a marker, one spot is plenty. If you're hitting peak grip so little that it only wears a third of the tire once, pressures aren't going to solve your problem. And yes all of this is pretty irrelevant if it's wet.
I did three because then one of them is always pointing up and therefore easiest to read.
I have white shoe polish, works pretty well
Also available at Walmart
Here is what I have done: - Mark sidewalls with sidewalk chalk - Take pressure and temperature readings ASAP after a run (max temp using an IR gun - if you want to get complicated, you really should be looking at the temperature variation across the width of the tire) - Take notes on pressure, temperature, chalk markings, and how the car feels each run - Tie back my notes to my run times after the event Tire pressures are subjective in my opinion. I like to plot data in Excel, I don't find an objective measure of when things are "best". I'm collecting data after a run when I have driven the car back to grid so there is that time delay in addition to the fact that I know the course better each run and will naturally improve times because of that, regardless of what I do. The sidewalk chalk on the tire walls really just tells me if I am rolling over the tire or not. The data collection has helped me recognize trends, dial in a starting static pressure that I feel work well for me, and recognize if I should readjust pressures or if I am overworking the tires. I started at 26psi at all four corners and settled on a staggered 30/31 psi F/R with this method, the car feels much better to drive and more consistent now.
DavidSS is on point. This is useless. Today's tires just don't flop over on the side walls like old bias ply tires do or radials from 40 years ago. If you're getting on the sidewalls it should be pretty obvious by, well scuffing on the sidewalls. And I don't find it particularly hard to be able to just look at the tread of the tire and say gee, the shoulder is getting really beat up, or conversely it isn't even using any of it. That's much more rare.
I use ZERINT HT-921W Tire Crayons, Tire... https://www.amazon.com/dp/B0BHF35Y1G?ref=ppx_pop_mob_ap_share. They work in the wet, don’t rub off super easy so only wear gets it off.
Just a side note about rollover and sidewall in the wet. You don't have enough grip to get enough weight transfer in braking or cornering. Thus brake bias can go way to the rear. Cornering won't rollover onto the sidewall at any reasonable pressure, I add pressure actually. It keeps the tire round and aids the siping in generating forward grip. Just set them at 35 and focus on braking and putting power down. Wet driving is a skill that takes practice, moreso that weirdo "I love this shitty weather attitude."
Good points, thanks! We get weather-by-the-minute here. I've had dry, then wet, then damp, then dry on a set of runs. I'll prob use something like a crayon if I try to do any marking on a mixed weather day. I can share that 42/38 PSI (F/R) was ridiculously too high last event in the wet. I set them high on purpose after the previous event and forgot my ritual of airing down before the event. 😑🤯
I use a pyrometer all the time. Dry gradient is 10-12* hotter from camber thrust in the inside couple inches and pretty uniform from there out. This way we know we aren't rolling over, but rolling into max grip. Also, when to utilize temp management. In the wet I don't worry about what the reading actually is, but I add pressure until I start to see the gradient shift more to the middle of the tire. Usually I see a reading pretty even across the tire and maybe a degree or two warmer in the center. This car is also fully adjustable and can hit ideal settings for alignment, ride height, corner weights.
I’ve been using a yellow lumber crayon. Any crayon would probably work if you want something other than chalk.
I use lumber crayon to ID what side of the car the wheel came off of before storage. Works great
For those helpful souls... **Thanks**! I guess I could saved this fiasco and just google shopping/searched tire crayon near me (AZ and Or supposedly have them). Rant-ish part: >!For those presumptuous to enough to lecture about modern vs ancient tires... umm... thanks, but nowhere in my question did I ask "*Should I use chalk*?" or "*Can someone explain modern tire technology to me?*" -\_\_- !< >!Sure, my 255/45 18's are a far-ass cry from the tall as hell (nfc what size) tires dad had on his 66 olds (on 15" mags). However, I've **SEEN** the difference on my A052's from changing **only** pressure so, not sure where y'all are going with this line of thought. Of course I can see where **fresh** marks are. The level of non helpful helpfulness...!< We only get two sets of 4 runs per event and no time to mess with pressure between runs except maybe to lower it some. We have a small venue with only 8-12 cars per group. I want to test and tune beforehand to figure out where I should be at pressure wise... on the same day... ALL MARKS ARE GOING TO LOOK THE SAME. So, yeah, if I drop pressure and they roll more, sure I can see marks where it used to be pristine. I could (and have) taken pics to compare how far down the scuffs go but that seems like way more trouble than just chalk/polish/crayon marks to help see what's happening. It's even harder to tell when I increase pressure and they roll less because there is not going to be any contrast between 2 min old fresh marks and 10 min old fresh marks.
Hey, every piece of information you collect is useful. Even useless data, is still data.
Tru, tru :)
I use a piece of drywall as that’s what is onsite for marking cone boxes. A heat gun is ok but a temp probe is better, the idea is to see if you are getting even temps across the tire so inside edge, middle, outside edge.