Rubber generates heat from strain cycles. More deformation, or higher cycle rate -> more hysteretic energy loss to heat. Cornering, or applying drive and brake torque, does generate strain and heat.marcush. wrote:that has been discussed at lengths for numerous times and still nobody came up with a satisfactory explanation why weaving should warm up tyres.
), repeat. BTW, doing this "on line" lest you pick dirt and whatever as the tires get hot. Thanks, though I'm not a "tire" person. Have worked with thousands of racing tires however, trying to make the car and the driver work around them....alelanza wrote:Great post, we need more tyre people around here
I know, what you want to say Marcus, and there is merrit to it, but I maybe would not use the "without any doubt" expression when it comes to tires.marcush. wrote:without any doubt it is wrong to talk of temperature as a means of declaring tyres conditioned correctly for exploiting their potential
User Advice
For most purposes, racing tyres will benefit from an appropriate 'Scrubbing in' procedure. This provides the best combination of performance and longevity under race conditions.
There are several difficulties that arise when using racing tyres if they are not scrubbed in prior to use. The most common is "Cold Graining", where the layer of the tread compound in contact with the track, fails in shear with the layer below. The result is a very visible low frequency, high amplitude rippling effect. This is more common with new tyres particularly when used in wet, damp or greasy conditions.
Avon Tyres Motorsport recommends that a standard scrubbing in procedure be used whenever possible (conditions and regulations allowing). This consists of subjecting the tyres through one gentle heat cycle, gradually loading them up whilst avoiding drifting the car. This should take about three to four laps of a circuit where the lap time is in the region of 60 to 100 seconds. The last lap should only be about 80% race speed. If possible, scrub in at least one new set of tyres during free practice, and put these aside for the race. In this way you will know that they have been balanced correctly, and have no slow punctures etc. Getting this done early is important as the qualifying session may become wet or be red flagged, which could force the use of new tyres in a race.
When regulations or circumstances do not allow the above procedure to be carried out, then the following should be borne in mind: -
*
Graining of the loaded front tyre can be avoided if it is ensured that they are fully up to temperature before pushing hard.
*
It is relatively easy to generate temperature in the driving tyres as they are transmitting power most of the time. The front tyres, however, will need to be given more time and be loaded up progressively before they will be 'In' fully. It should be noted that it is the loading of tyres that introduces the significant heat, not sliding or wheelspinning.
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For qualifying, the best results have been shown to have been achieved when the front and rear tyre temperatures are the same when measured at the base of the tread. If pushed too early, the rear will come in before the front causing understeer, and taken to the extreme, cold graining as detailed above.
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It is quite possible to get the rear tyres to go off before the front tyres come in, which will lead to a car that is never balanced, making set-up and qualifying very difficult.
Thus to get the best from a set of scrubbed tyres, look after the rear tyres by not using full power out of corners, and instead work the front tyres progressively without inducing large amounts of understeer. When the fronts are fully up to temperature, go for a time (really hooked up lap). Push hard for 2 to 3 laps, and then back off the pace for a lap to allow the tyres to recover, and to get some clear track. Repeat this procedure for the best results.
It should be noted that there is always going to be a slight performance peak from new tyres, but it will only be possible to take advantage of this if the car is balanced on its tyres. A correctly scrubbed in set of tyres will always give more consistent performance over its lifetime than a set that has been used hard from new, even if it hasn't grained.
Warming of the tires and conditioning them (a first cycle scrub) are too different subjects. I am only referring to tire warming, not conditioning.747heavy wrote:what AVON has to say in regards to tire conditioning:
it is in part opposing to speedsense recommendation of "small burnouts", take your own pick - there are different ways to skin a cat.
But keep in mind that rubber is a poor heat conductor in general.
One of the most efficient methods of tire heating - the use of micro waves - is unfortunately banned in most racing series, but was used with geat success by Audi in LeMans before the ban.
User Advice
For most purposes, racing tyres will benefit from an appropriate 'Scrubbing in' procedure. This provides the best combination of performance and longevity under race conditions.
There are several difficulties that arise when using racing tyres if they are not scrubbed in prior to use. The most common is "Cold Graining", where the layer of the tread compound in contact with the track, fails in shear with the layer below. The result is a very visible low frequency, high amplitude rippling effect. This is more common with new tyres particularly when used in wet, damp or greasy conditions.
Avon Tyres Motorsport recommends that a standard scrubbing in procedure be used whenever possible (conditions and regulations allowing). This consists of subjecting the tyres through one gentle heat cycle, gradually loading them up whilst avoiding drifting the car. This should take about three to four laps of a circuit where the lap time is in the region of 60 to 100 seconds. The last lap should only be about 80% race speed. If possible, scrub in at least one new set of tyres during free practice, and put these aside for the race. In this way you will know that they have been balanced correctly, and have no slow punctures etc. Getting this done early is important as the qualifying session may become wet or be red flagged, which could force the use of new tyres in a race.
When regulations or circumstances do not allow the above procedure to be carried out, then the following should be borne in mind: -
*
Graining of the loaded front tyre can be avoided if it is ensured that they are fully up to temperature before pushing hard.
*
It is relatively easy to generate temperature in the driving tyres as they are transmitting power most of the time. The front tyres, however, will need to be given more time and be loaded up progressively before they will be 'In' fully. It should be noted that it is the loading of tyres that introduces the significant heat, not sliding or wheelspinning.
*
For qualifying, the best results have been shown to have been achieved when the front and rear tyre temperatures are the same when measured at the base of the tread. If pushed too early, the rear will come in before the front causing understeer, and taken to the extreme, cold graining as detailed above.
*
It is quite possible to get the rear tyres to go off before the front tyres come in, which will lead to a car that is never balanced, making set-up and qualifying very difficult.
Thus to get the best from a set of scrubbed tyres, look after the rear tyres by not using full power out of corners, and instead work the front tyres progressively without inducing large amounts of understeer. When the fronts are fully up to temperature, go for a time (really hooked up lap). Push hard for 2 to 3 laps, and then back off the pace for a lap to allow the tyres to recover, and to get some clear track. Repeat this procedure for the best results.
It should be noted that there is always going to be a slight performance peak from new tyres, but it will only be possible to take advantage of this if the car is balanced on its tyres. A correctly scrubbed in set of tyres will always give more consistent performance over its lifetime than a set that has been used hard from new, even if it hasn't grained.
