When are slicks done

[jwalk]

This year I switched to Michelin and Pirelli slicks. There are a few dimples across the width of the tire for wear indicators. My question is when you wear through the dimple is the tire done? Or is there 20%-30% left? The outside dimple is about gone but the middle and inside are still there.

[catwood]

For me, when the cords start showing.

[bluesrt]

:fpopcorn: this is gonna be a good one

[Arizona Vipers]

Depends on how important lap times are to you as well. For some they get rid of them when they get too slow.
Otherwise, I have run many sets of Pirelli's and Michelin's until they cord. They last a LONG time, longer than you expect.

[TooBlue]

This year I switched to Michelin and Pirelli slicks. There are a few dimples across the width of the tire for wear indicators. My question is when you wear through the dimple is the tire done? Or is there 20%-30% left? The outside dimple is about gone but the middle and inside are still there.

If your tire is wearing on the outside and not in the middle or inside you aren't running enough neg. camber. Your tire is rolling over in turns wearing the outside wear indicator dimples.
You can check this with a heat gun with a tire probe. Take a heat reading on the inside, outside and middle of the tire when hot. Obviously you want to adjust to get the same temp. across the tire. Uneven temperature on inside, outside or center only is an alignment issue. If the inside and outside are hotter than the center, you need more tire pressure. When the center is hotter than the outside and inside of the tire, you have too much tire pressure. Take these readings as soon as you can when coming off the track. I have one of my buddies take readings (temp and tire pressure) ASAP when I exit from the track.
If you don't have a heat gun, you can tell if your car is aligned correctly or correct tire pressure for your driving style by the uneven wear on the tire wear indicators, like you did.

It has been my experience that you know when slicks are finished. They lose grip and feel "greasy" when warmed up. If you have tracked your car enough (which I assume you do since you are running slicks) you will feel and know you aren't getting the traction or a "comfortable" speed going in, during and exiting a corner. Slicks will fall off in a hurry. Sometimes in the middle of a session.
Like I said, you will feel it.

I feel my car is set up correctly because I have had slicks "wear out" and the tire still had wear indicator dimples.

[catwood]

I'm going to conflict a bit with TooBlue, YMMV. I would not use a heat gun, only a probe. And tire temps on each tire should be within 10% Inside-Middle-Outside. But tires left to right and front to back can vary greatly....I don't worry about that. It's only the heat across the tire being measured. Also, do it the same every time. Start with a tire and go around the car. Always start with that tire and go the same direction, make it a habit. I have a chart I write it down on with notes.. I make small adjustments based on heat, not pressure. .5# to 1#

[06SRTCoupe]

Slicks are done when they become slick. You're welcome.

[09 ACR]

What must HPDE drivers use as a rule is 6 heat cycles (1 heat cycle every time you go on track) most slicks will then start to really lose grip. if you want to be fast you have to change tires after 6 cycles.

if you don't want to have to work to just buy Slicks, use them for 16-18 heat cycles (always looking for wear to make sure set up is not wrong) once you get past 16-18 cycles slicks become what I would call dangerous they are very slippery. by the time you get to 18 heat cycles you will be driving faster then you have before and going slower. just no traction this is why they become dangerous

[TooBlue]

I'm going to conflict a bit with TooBlue, YMMV. I would not use a heat gun, only a probe. And tire temps on each tire should be within 10% Inside-Middle-Outside. But tires left to right and front to back can vary greatly....I don't worry about that. It's only the heat across the tire being measured. Also, do it the same every time. Start with a tire and go around the car. Always start with that tire and go the same direction, make it a habit. I have a chart I write it down on with notes.. I make small adjustments based on heat, not pressure. .5# to 1#

I agree. I said heat gun and probe because my Joes Racing tire probe plugs into my heat gun. Like Catwood said, the probe is the only real accurate way to check tire temps. The heat gun/probe instrument I have is nice because I use the probe plugged into the heat gun for tires. I also use the heat gun by itself to check and monitor caliper and rotor temps to make sure they are consistent throughout the track day. If one caliper is getting hotter than the others can be a sign of bad caliper piston seals or some other problem in the caliper. One extra hot rotor can mean a wheel bearing hub is probably going bad. I also randomly check the heat on other parts of the car for uneven heat temps. The header temp. from side to side for example.
I also use the heat gun on the wheel hubs on my trailer after a long trip to a track. In past experience with our track gang has been trailer hub failure only happens when the car is loaded in the trailer, it's 102* and you are in the middle of nowhere.
I just walk around the trailer and shoot the hubs at each stop for fuel.

I also use the heat gun to measure the temp. of the wife's forehead when I tell her I broke another expensive part at the track...:furious:

I also agree with the rest of your post except measuring only heat not pressure. One overfilled tire will run cooler and therefore give a different reading than the other three. If the tires are all different pressures you will have a different temp on each tire. I experienced this from running the half mile in my TT. If the tires aren't at even pressure the launch will be affected and again when the car spools up.

Last point. ( I promise..) If you don't use nitrogen in your tires, make sure the air compressor has a moisture collector.
A tire with moisture in it will build pressure faster and have a bigger variance in temp and pressure when the tire goes from cold to hot on track. Nitrogen is the way to go if available.

Good additional info though...IMO

[38D]

Take a heat reading on the inside, outside and middle of the tire when hot. Obviously you want to adjust to get the same temp. across the tire. Uneven temperature on inside, outside or center only is an alignment issue.


And tire temps on each tire should be within 10% Inside-Middle-Outside.

A 10% spread is the correct rule of thumb for a fast setup. Even temps may be good for wear, but it will be slow. And you should be hitting at least 180f minimum, and 200f is even better. Tire compound can make a bit of difference.

[TooBlue]

A 10% spread is the correct rule of thumb for a fast setup. Even temps may be good for wear, but it will be slow. And you should be hitting at least 180f minimum, and 200f is even better. Tire compound can make a bit of difference.

I agree. I guess I should have elaborated more but my post was already long enough. Getting the tires exactly the same is pretty much impossible.
For instance, at Road America the drivers side front tire builds a lot more heat and wear. You will obviously have to compensate for things like this.

OP.. as pointed out from the informative posts above, there’s some important factors to consider as far as running race tires (slicks)

[str5010]

What must HPDE drivers use as a rule is 6 heat cycles (1 heat cycle every time you go on track) most slicks will then start to really lose grip. if you want to be fast you have to change tires after 6 cycles.

if you don't want to have to work to just buy Slicks, use them for 16-18 heat cycles (always looking for wear to make sure set up is not wrong) once you get past 16-18 cycles slicks become what I would call dangerous they are very slippery. by the time you get to 18 heat cycles you will be driving faster then you have before and going slower. just no traction this is why they become dangerous

The definition of a heat cycle can be really misleading considering how varied each HPDE organization may run their event. I've been at some one where day could consist of 3, 20 minute sessions and I've been at others which could follow a format of 6, 30 minute sessions. Therefore a single heat cycle as far as I've always been taught is just as it sounds - a tire going from ambient temp up to operating temp on track and then returning to rest. So at my last two day event I had a total of 12, 30 minute track sessions with ample down time in between for a total of 12 heat cycles.

[catwood]

I agree. I said heat gun and probe because my Joes Racing tire probe plugs into my heat gun. Like Catwood said, the probe is the only real accurate way to check tire temps. The heat gun/probe instrument I have is nice because I use the probe plugged into the heat gun for tires. I also use the heat gun by itself to check and monitor caliper and rotor temps to make sure they are consistent throughout the track day. If one caliper is getting hotter than the others can be a sign of bad caliper piston seals or some other problem in the caliper. One extra hot rotor can mean a wheel bearing hub is probably going bad. I also randomly check the heat on other parts of the car for uneven heat temps. The header temp. from side to side for example.
I also use the heat gun on the wheel hubs on my trailer after a long trip to a track. In past experience with our track gang has been trailer hub failure only happens when the car is loaded in the trailer, it's 102* and you are in the middle of nowhere.
I just walk around the trailer and shoot the hubs at each stop for fuel.

I also use the heat gun to measure the temp. of the wife's forehead when I tell her I broke another expensive part at the track...:furious:

I also agree with the rest of your post except measuring only heat not pressure. One overfilled tire will run cooler and therefore give a different reading than the other three. If the tires are all different pressures you will have a different temp on each tire. I experienced this from running the half mile in my TT. If the tires aren't at even pressure the launch will be affected and again when the car spools up.

Last point. ( I promise..) If you don't use nitrogen in your tires, make sure the air compressor has a moisture collector.
A tire with moisture in it will build pressure faster and have a bigger variance in temp and pressure when the tire goes from cold to hot on track. Nitrogen is the way to go if available.

Good additional info though...IMO



i didn't mean to say I don't measure pressure. I do. But I don't adjust for pressure, I adjust the pressure based on heat readings. So if a tire is 40# hot and the middle is 15% hotter for example than the inside/outside, I'lll drop it 1/2 lb. that's an example only. I have found it doesn't matter when you make the adjustment, right then hot or just before the next session after they cooled a bit. One other thing I do is I go back and look at my hot pressures for a particular track ( I run willow mostly) and set the tires to those temps before I corner balance. Yes, they are different but it seems to give a better balanced car.

[stradman]

The definition of a heat cycle can be really misleading considering how varied each HPDE organization may run their event. I've been at some one where day could consist of 3, 20 minute sessions and I've been at others which could follow a format of 6, 30 minute sessions. Therefore a single heat cycle as far as I've always been taught is just as it sounds - a tire going from ambient temp up to operating temp on track and then returning to rest. So at my last two day event I had a total of 12, 30 minute track sessions with ample down time in between for a total of 12 heat cycles.

What I would like to know is how the operating temp will vary from individual to individual because we don't all lean on or tires in the same way and how that is reconciled to a "heat cycle". Perhaps there is a temp that the tires have to hit in order to be classed as a "heat cycle". Anything less may not not lead to material change in the tire composition. Lets face it if someone is 3-4 seconds slower around a lap then I have to assume that his tires are not reaching the same temp in his 30 minute outing as the guy who is quicker.

[TooBlue]

A lot of good info in this thread. Best part is the info comes from Viper guys with quite a bit of track experience and not bench racers.

I was in a very bad car accident in January and will be in recovery till this Fall. All this track talk is making me miss tracking this year even more ....

Everybody does things a little different but I think we are basically saying the same thing.
You can’t just go by wear on the indicators alone.

[The Stig]

Do a few hard laps. use a temp gauge probe across face outer edges and middle that will give you an indicator on how the tire and car is working. Buy a tires SOFTNESS gauge. depending on track and turns- you might have to adjust tire pressure- which in turns changes your spring rates some. This could correct some of your wear problem along with a correct setup/alignment

https://www.youtube.com/results?search_query=chassis+setup

[FrankBarba]

You that they are done when you hit a wall...

[NT-ACR]

You that they are done when you hit a wall...

I wouldn't quit my day job, Frank.

[stradman]

I wouldn't quit my day job, Frank.

:lol2:

[Racingswh]

We got 12 sessions out of a set of Michelin mediums 31/71 rear, 30/65 front . Last 10 sessions were 25 minutes. Rears were greasy and fronts were showing cords.

[kriskyk]

Do normal street tires have heat cycle considerations like slicks?

[catwood]

Do normal street tires have heat cycle considerations like slicks?

Street tires are done (meaning slow) 30 days after hitting the pavement. I learned this from Viperdays where we had to run the OEM tire.

[str5010]

What I would like to know is how the operating temp will vary from individual to individual because we don't all lean on or tires in the same way and how that is reconciled to a "heat cycle". Perhaps there is a temp that the tires have to hit in order to be classed as a "heat cycle". Anything less may not not lead to material change in the tire composition. Lets face it if someone is 3-4 seconds slower around a lap then I have to assume that his tires are not reaching the same temp in his 30 minute outing as the guy who is quicker.

A fair point that would vary according to the construction of each tire.

[Bill Pemberton]

Cat ..............Viperdays was a very long time ago and DOT Comp Street tires and many other street tires are quite sticky and really bear no resemblance to the rock hard donuts we raced on 10-18 years back, imho.

I ran a set of Pirelli slicks on my race car three full weekends, and on the fourth they ran okay during qualifying, but they disappeared during the race. Four laps in they were toast and I was dirt tracking the next 25 minutes , struggling to stay ahead of two drivers and not succeeding. Still had dimples , but they are gone.......................

Heat cycles , I can only count mine, as they were used rubber devices from a World Challenge Event. Just an example that tread is not always an indicator. Now if someone wanted to still use them for a High Performance Driving Event , no problem , there is life in them , just not in the Fast Lane.

[catwood]

Cat ..............Viperdays was a very long time ago and DOT Comp Street tires and many other street tires are quite sticky and really bear no resemblance to the rock hard donuts we raced on 10-18 years back, imho.

I ran a set of Pirelli slicks on my race car three full weekends, and on the fourth they ran okay during qualifying, but they disappeared during the race. Four laps in they were toast and I was dirt tracking the next 25 minutes , struggling to stay ahead of two drivers and not succeeding. Still had dimples , but they are gone.......................

Heat cycles , I can only count mine, as they were used rubber devices from a World Challenge Event. Just an example that tread is not always an indicator. Now if someone wanted to still use them for a High Performance Driving Event , no problem , there is life in them , just not in the Fast Lane.

Hi Bill. I didn't mean DOT comp tires like hoosiers. I was speaking about Pilot Sports and the like...true street tires. And yes, Viperdays was long ago.....miss those things.

[Arizona Vipers]

We got 12 sessions out of a set of Michelin mediums 31/71 rear, 30/65 front . Last 10 sessions were 25 minutes. Rears were greasy and fronts were showing cords.

Here's your answer, on the Michelin's or Pirelli's, run them till they cord.

[catwood]

Here's your answer, on the Michelin's or Pirelli's, run them till they cord.

Where do you get your slicks? I might switch from Hoosiers to full slicks for a few events.

[BlueAdder]

Where do you get your slicks? I might switch from Hoosiers to full slicks for a few events.

Here's one place: https://rogerkrausracing.com/index.php/avon-tires/

Those are Avon but basically you can find race shops that sell proper slicks.

[catwood]

Here's one place: https://rogerkrausracing.com/index.php/avon-tires/

Those are Avon but basically you can find race shops that sell proper slicks.

Thanks....I'll look there when I get some time

[Bill Pemberton]

Frankly , true street tires are so far ahead of what we raced on back in the olden days and many are quite fast ( especially BFG Rivals , Bridgestone RE71s, and even Michelin Pilot Sport 4S ). Just politely disputing the general comment that they (Tires ) are shot 30 days after hitting the pavement , as that is clearly not accurate - we have a lot of new owners who often take statements like this to heart. We ran on tires back in Viper Days that would last some of us an entire Season ( I was never able to do that, ha) , and thank goodness the Tire Manufacturers have kept pace with the performance machines of today. We ran around with a measly 450 HP, when today even vehicles like a Mustang GT have 460. Just my humble opinion, and I too miss the fun of Viper Days. I am lucky, though, as we have the Viper Rendezvous just down the road in Hastings, Nebraska, and for the 60 or so Vipers that show up each year in June, many are folks who ran in Viper Days and they comment how similar it is to the camaraderie and competition of those hallowed days!

[FrankBarba]

Personally I would not run full slicks unless your suspension is tuned for it. Slicks are much
different than the tires one would run at a NASA, or SCCA event. I have known people to put slicks
on and break suspension parts. Just my opinion. And I wouldn't quit my day job. I was just saying
that if you think your tires are gone why chance it. Everyone drives differently and handle different
situations in their own way. Just be careful on the track.

Pictures would help....

[catwood]

Bill, we are going to have to agree to disagree. I didn't say "shot" but rather "done". Done meaning they are slow and not longer competitive. When I ran street tires I would get a ton of sessions but fresh tires picked up several seconds from tires just a few months old.

[Bill Pemberton]

No disagreement there, but you did not clarify , you just stated they got old in 30 days on the pavement. I would agree with your assessment of 30 days of usage on the track.

[catwood]

Here's one place: https://rogerkrausracing.com/index.php/avon-tires/

Those are Avon but basically you can find race shops that sell proper slicks.

After looking at the pricing I think I'll stick with the R7s for now. I just picked up a set locally in 18" for $1720, tax, shipping, mounting, lifetime balance (ha ha) included.

Note...these are not for my ACR but it's a Gen 2 & 4 size I used to run.

[BlueAdder]

Gotta pay if you wanna play lol
I would also stick to Hoosiers, actual slicks are too damn expensive and I'm not racing either. Now, if I was racing and somewhat competitive, I would make the switch.
For now the Kumhos are just fine (besides the fact that I have to change them so damn often)...

[Arizona Vipers]

Gotta pay if you wanna play lol
I would also stick to Hoosiers, actual slicks are too damn expensive and I'm not racing either. Now, if I was racing and somewhat competitive, I would make the switch.
For now the Kumhos are just fine (besides the fact that I have to change them so damn often)...

For me this isn't true, the Michelin's are about $300 a set more, but last much longer than the Hoosiers.

[BlueAdder]

For me this isn't true, the Michelin's are about $300 a set more, but last much longer than the Hoosiers.

Michelin > Hoosier > Kumho
Depends on the compound tho, no? Soft won't last you as long as getting some medium, yea?

[Arizona Vipers]

Michelin > Hoosier > Kumho
Depends on the compound tho, no? Soft won't last you as long as getting some medium, yea?

Just get hards, the hards are much faster than the Hoosiers. You can't get the softs in our sizes. You can get the mediums, but you have to get your best lap in pretty quick versus the hards.

[catwood]

For me this isn't true, the Michelin's are about $300 a set more, but last much longer than the Hoosiers.

quantify "much longer" if you could please.

[stradman]

For me this isn't true, the Michelin's are about $300 a set more, but last much longer than the Hoosiers.

Pirelli DH??

[Dr.Ron]

I run Hoosier A7's. The majority of the time there is still tread left when they heat cycle out. They get slippery so that's when I change them. A couple of times the cords started showing, but on the inside or outside edges, not the tread. I run an aggressive camber setting.
I get about 12-14 heat cycles on a set.

Ron

[1ststrike]

After the dimples are gone on any part of the tire I would not run them. Especially at Road America. Lots of concrete walls

[Arizona Vipers]

quantify "much longer" if you could please.

Why don't you try a set? we all run different tracks, different driving styles etc. For me, the Michelin's are faster and last longer than A7's

- - - Updated - - -


Pirelli DH??

The Pirelli DH's last a long time too but are MUCH more expensive than even the Michelin's. about 50% more than the Hoosiers

[13COBRA]

Why don't you try a set? we all run different tracks, different driving styles etc. For me, the Michelin's are faster and last longer than A7's

- - - Updated - - -



The Pirelli DH's last a long time too but are MUCH more expensive than even the Michelin's. about 50% more than the Hoosiers

Do you prefer A7s over R7s?

I've tried both and have gone faster on the R7s, but who knows, there's always been more factors than just a tire change.

[catwood]

Do you prefer A7s over R7s?

I've tried both and have gone faster on the R7s, but who knows, there's always been more factors than just a tire change.

For me, the A7s come up to temp faster and went away faster. Hoosier claimed it was the same compound. There were fast out of the box, maybe faster than R7s, hard to say. But the R7 seem to stay more consistant over a session and faded at a slower rate.

[13COBRA]

For me, the A7s come up to temp faster and went away faster. Hoosier claimed it was the same compound. There were fast out of the box, maybe faster than R7s, hard to say. But the R7 seem to stay more consistant over a session and faded at a slower rate.

Those are my exact impressions as well.

[catwood]

Why don't you try a set? we all run different tracks, different driving styles etc. For me, the Michelin's are faster and last longer than A7's

- - - Updated - - -

And different cars (panoz). I'll shop around more for a set. 13Slobra sent me a site to look at, not sure if there are others. I also need to get the specs on them to get the correct size. I don't want to redo the set up on the car.....ugh.

[Arizona Vipers]

Do you prefer A7s over R7s?

I've tried both and have gone faster on the R7s, but who knows, there's always been more factors than just a tire change.

A7's are MUCH faster. If you didn't go faster you are probably running to much psi. The A7's will wear out much sooner than R7's though, I go through front A7's in 4 sessions. R7's seemed to last forever.

[Dr.Ron]

A7's are MUCH faster. If you didn't go faster you are probably running to much psi. The A7's will wear out much sooner than R7's though, I go through front A7's in 4 sessions. R7's seemed to last forever.

What pressures do you run cold and hot?

[13COBRA]

A7's are MUCH faster. If you didn't go faster you are probably running to much psi. The A7's will wear out much sooner than R7's though, I go through front A7's in 4 sessions. R7's seemed to last forever.

Thanks for the heads up.

[Racingswh]

I like slicks now. I won't go back. 31/71 rear, 30/65 front Michelins, 325/705 rear, 305/645 front Pirelli's. 22 PSI front, 20 PSI rear cold pressures.

I had on A's in the heat at Watkins Glen and the car moves around a lot late in the sessions. Fine for a track day tire but they wear out fast. Better off to run R7's IMO EXCEPT if you're going to be running in the colder months. A's like 140 degrees F and R's want to be over 180 degrees F to work optimally.

Most I have ever gotten out of a set of A's on the Viper is 31 sessions rear, 18 front. Funny enough I set down a personal best on those 31 session A's at Summit Point Main on their 31st session. When I came I was riding on the cords.

[Arizona Vipers]

I like slicks now. I won't go back. 31/71 rear, 30/65 front Michelins, 325/705 rear, 305/645 front Pirelli's. 22 PSI front, 20 PSI rear cold pressures.

I had on A's in the heat at Watkins Glen and the car moves around a lot late in the sessions. Fine for a track day tire but they wear out fast. Better off to run R7's IMO EXCEPT if you're going to be running in the colder months. A's like 140 degrees F and R's want to be over 180 degrees F to work optimally.

Most I have ever gotten out of a set of A's on the Viper is 31 sessions rear, 18 front. Funny enough I set down a personal best on those 31 session A's at Summit Point Main on their 31st session. When I came I was riding on the cords.

I've got two sets of softs for you with only one heat cycle on each! Send me some labels! :dude3:
Interesting you starting the rears lower pressure, you are getting more heat out of the rears than the fronts?