It is interesting that Tire Rack will heat cycle your high performance street tires before shipping. They have a brief explanation in their website. I was hopeful they'd do my Hoosiers.... only offered on their tire & rim packages.
"An analog man living in a digital world"
Thx for the heads up !!! Makes more sense than using track time for that...
"An analog man living in a digital world"
You want them to have a specific test and break-in-procedure for every single size, car class, and (except for the spec classes) chassis /engine combo? Do you suddenly want racing tires to be even more ridiculously expensive than they are?
Call them and ask.
Glancing at the Hoosier road racing line, I see about 30 different sizes of bias ply slicks, about 38 different sizes of radial slicks, 55 different sizes of DOT radials, and 13 different sizes of DOT bias ply tires. That's over 130 different sizes of tires, many of which come in multiple compounds. And that's just the road-racing dry tires. They also make tires for drag racing and oval-track racing, both of which have radically different constructions from what we use.
And you want what, exactly? Would you be happy with a single-sheet with some specific parameters, or will you require a 600-page tome with specific numbers for every track and possible setup configuration, with detailed data including the exact throttle position and angle you hold your head at?
So FSAE teams have a specific break-in procedure to provide consistency for their testing, and then you say that this has no bearing on extending tire performance? So why do they bother with it if as you say, break in is "myth." You can just beat the snot out of your unstable tread structure to your hearts content, and your tires will be none the worse for wear because of it.
Perhaps you'll do us all a service and dispel that pesky engine break-in myth, too.
If it has no bearing on tire performance, and the detailed specific procedure you want was developed, as you say, by the TEAMS, why the repeated demands from the manufacturers for specific data?
Personally, I've found that whether or not tire break-in helps with long-term tire life really depends on the specific tire compound and construction, and what type of car its on.
The crappy street tires we ran on the Legends cars didn't seem to need any break in. This was mainly due to the fact they had no grip to speak of whether they were brand new or 100 races old. You just tossed the thing into the turn, rolled onto the throttle, and prayed to the traction gods the inevitable power-slide would end sometime before you hit the outside retaining wall.
The synthetic-rubber BFG's we ran on the World Challenge car in 1999 & 2000 absolutely needed to be broken in. This was due to whatever crazy release compound they used. If you tried to go fast on the first heat cycle it wasn't a question of if you would wreck the car, it was how hard you'd auger it in. I've driven on black ice, and I've driven FM's in pouring rain with a full dry setup and neither experience was as terrifying as breaking in those BFG's on the Prelude.
On the FM's I've got the most complete data. The Goodyears don't seem to be affected by following a break-in procedure, at least on the older construction ones. I haven't bothered to test it out on the new construction tires as they don't seem to behave much differently (they're just faster).
The Hoosiers we ran from 2005-2007 definitely needed a break-in cycle at low speed. They would simply not build pressure consistently on the first heat cycle, and if you ran them hard for a full session they would never be quite as fast as when you did a good break in (by a couple of tenths). The only way the tire would perform consistently at all was if you broke them in, ideally the day before qualifying. They were still weird anyway: the fastest heat cycle even with a good break in was the third & fourth ones.
On the FF cars, the F1600-series Hoosiers we run seem to be much more consistent. I don't have enough data to say definitively either way if break-in matters.
So nice to know that my two decades of racing experience, across a variety of platforms & tire types, in hundreds races never actually happened according to you.
Not worth a light if you haven't got silver rear view mirrors though.....
Thx for the heads up.... now, where'd I put that can of silver spray paint...
"An analog man living in a digital world"
I would not agree. Secondly, a study does not have to be directly related to motorsports to be relevant. Almost all of my race engine development start with SAE studies that are not race engine specific.
On this current subject there could be papers from Materials type journals that would be relevant.
Brian
First, I should state that my original question was too general. There are clearly some demonstrated benefits to stabilizing the tire carcass and cleaning the thread surface. What has not been demonstrated is that break-in extends a tire's service life.
So, regarding tire service life, your two decades of knowledge mean nothing if it is not backed by a scientific type study that you performed. Your knowledge is no more valid than the almost century of knowledge the FBI thought they had developed. The FBI forensic lab was certain that their results were valid beyond a reasonable doubt. The whole legal system blindly accepted their results.
Brian
Correction. It means nothing to YOU.
Believe what you like, but most of us tend to accept advice from folks whose opinions often turn out correct when ignored. This is especially true if that advice is counter to their short-term interest (don't scrub, trash your tires sooner, buy more tires - that seems to be what you recommend).
I can equally well cite "scientific type studies" that produced false conclusions for years, decades, and perhaps centuries (the Michelson-Morley experiment threatens to be one of the more monumental). Karl Popper again.
Caldwell D9B - Sold
Crossle' 30/32/45 Mongrel - Sold
RF94 Monoshock - here goes nothin'
Brian:
You are arguing you case like a cloistered academic.
The point of racing is to win. Not to publish papers based on some academic study. At least that is the way I look at the issue.
Some years back, Goodyear made a tire compound that was a great qualifying tire. The tire was good for a second or more over the next best option. Problem was that the tire would not last a race distance with any degree of confidence. All the drivers that year, used the soft tires for qualifying but switched to sticker tires with the harder compound for the race.
However, every time you cycled a tire, heating and cooling it, the tire gets just a little bit harder. The trick was not to ware the tire down as it was heat cycled. After about 8 heat cycles, it was determined that the tire was perfect for a race distance.
The tire was still 3/4 a second faster than the next best option in sticker condition. Those tires were used to win an SCCA national championship. The advantage that the tires gave, allowed the driver to run at just below maximum and the tires were good for an additional race.
I think this in an example of what you are saying does not happen.
What are some thoughts on scrubbing in rain tires? Also why would the break-in process not just be part of production similar to the service tire rack does?
Last edited by Adam Brouillard; 09.08.13 at 1:21 PM.
It's a good point, what do you do with rains?
Wet tyres are a little different, they generally work best in full rain when the edges to the patterns are sharp (cut cleanest through the water) so any kind of scrubbing-in just hurts those edges.
Pending on space availability and wheels, I would have a set of new wets ready, and a set of old beaters mounted and if it's wet, use the new ones, if it's a drying track and there's a choice of wet or dry, maybe the old rock hard worn out wets would be good.
Oh, and I've been asked about possibly scrubbing dry tyres in a wet practice session. No, you would be putting miles on them but you would never be able to load the compound a 'tear' the surface to warm it through. And the water has a somewhat unfortunate cooling effect too.....
Pete lackinginimaginativetextofasundayevening.
If I run a set of stickers at qualifying pace then the rubber tears...scrub the tires, let them sit for atleast 24 hours and the rubber wears evenly without the graining...
Lap times? Goodyears were fastest on 3rd heat cycle if there was any rubber left to run on.
Hoosiers have been quickest first session after a scrub. No difference from stickers vs scrubbed except the tire doesn't grain and last much longer..
I race a Formula Mazda...notoriously hard on tires.
Bringing this back up. What are people's thoughts on the 24 hour rest period. Obviously something magical does not happen at the 24 hour mark and the tires are probably at ambient within an hour or 2. Is there really some chemical process going on in the meantime? Where did the 24 hour number come from?
Hoosier's website explains why you should certainly follow their new tire break in procedure for maximum grip as well as longer life. Their recommendation is (copied from their website):
Tire Break-In Procedure
Proper break-in will not only affect initial performance but will increase the competitive life of the tire.
The procedure can be broken down into phases.
1st phase: The initial run
2nd phase: The length of the time the tire is allowed to "cure"
The Initial Run Heat Cycle
The first laps for the tire are critical for setting up the durability and competitive life. The first session should consist of no more than 10-15 minutes of running. The early part of the session should be run at an easy pace, with the speed gradually increased until the end of the session. The final lap should be run at the fastest possible speed. The intent is to achieve maximum tire temp on the last lap. At this point the car should be brought in and the tires allowed to cool at a normal rate.
During the initial run-in process, the inflation pressure should be 3-5 psi higher than you would normally use. The best progression would have the driver taking 4-7 laps to accomplish this break-in. Each lap should be approximately 7-10 seconds a lap faster than the previous lap. The goal is to have the tire temp as high as possible on the last lap without "shocking" the tire during the warm up laps. In essence, no wheelspin, late braking, or sliding. The last lap should be at, or very close, the maximum possible.
"Cure" Time
After completing the initial run phase, the length of time the tire is allowed to set is possibly more important. The barest minimum for this process to be beneficial is 24 hours. (Not "the next day"). Any less than this is a waste of time. The best situation would allow a week before using the tire again.
Proper tire management is a difficult process. To accomplish this almost always requires a second set of wheels. The payoff is greatly increased competitive tire life.
Following the recommended break-in procedure will require a lot of planning to make it work. The benefits to doing it right include greatly increased tire life as well as consistent performance and durability under stress. Please make an effort to educate your team on the importance of this. It can save you a lot of money.
Tire Temperature Recommendations
For best performance the expected temperature range will vary from track to track. Generally, optimum traction will be generated when the pit lane temps show 180-200 degrees in Roadrace applications, and 140-150 degrees in an Autocross application.
Note: Use of static infra-red pyrometers is an inaccurate method to monitor tire temps.
Brian is asking about a scientific test, a real test with proven data.
This is Hoosier telling you what to do without prof that what they are telling you is true.
At least this is how I understand his question.
Mark Filip
For sure, proof is possible, but you're gonna have to pay for it; you can't expect the tyre companies to fund the scientific research, bearing in mind they're going to need a car that they have unfettered access to, as well as a driver that's worth the name peddling said car, run by a team that has no axe to grind nor advantage to take. If you ever find such a scenario, take a picture....
There are some tyre manufacturers who will deliver the rubber and then knob off, never to be seen again, and leave you to work it out on your own. Seems to me Hoosier and that big-eyebrowed ex-tyre chap are giving you the benefit of their experience without charge. Take it or leave it I reckon?
A long rest period is beneficial, not only after scrubbing, but after the initial build and curing. Some of the more durable molecular bonds take a relatively long time to develop, and these are necessary for durability and consistent longer-term performance. Another factor in improved performance after a rest period is internal stress relaxation. That is best achieved if left inflated, since the relaxation occurs in the shape it will have in use.
I personally saw this most directly in the performance of Firestone air springs. When I was durability-testing air springs at our Akron research facility, air springs that were tested within a day or 2 after curing almost always showed less durability (sometime by more than a factor of 10 for number of cycles completed) on the same test as nominally-identical air springs that sat post-cure for at least a week. And air springs that made it through the first few thousand cycles and were able to stabilize/stress-relax would usually run a very long time.
How long (several hours, a day, or a week) it takes for a particular tire to stabilize/optimize after initial cure or scrubbing will, of course, depend on the compound chemistry and the construction. However, a significant post-scrub/cure rest period is almost always needed.
Dave Weitzenhof
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