Scraping a tyre?

[raymondu999]

I've recently seen either on a BBC or Sky feature of some sort on F1 some mechanics sort of slicing or scraping the top surface of a used set of tyres. What exactly are they doing? Here's an example:

[marcush.]

ray,as soon as you go offline after doing a hot lap(s) the tyre will pickup a lot of debris and gum from the track (one of the reasons why drivers are weaving in pace car periods!)
So when the guy is coming into the pits the tyre guy and engineer will have no way to look at the workpattern on the tyre .So you need to clean the tyre to give a chance of evaluation of the state of affairs.

This is just normal pitcrew work around the world and the big chance to detect any damage to yout tyres .Every racer needs to perform this work at least for his own safety ,and to learn about the wear patterns .you will also learn about the tyre compound...it will give you an idea about the stick it still provides..worn out rubber does not produce the adhesion anymore after too many cycles..

A green track will not litter your tyre with debris of course...so this gets worse and worse over race weekends.And some people have certainly trouble to get rid of the PICKUP...so you ease the work of the driver in his warmup lap making things more predictable.

[jordangp]

It's not only in F1 either. Team boss Andreas Ericsson was scraping tyres for Tanner Foust at this weekend's ERC round at Lydden Hill.

[Jersey Tom]

As mentioned, is used to clean the crap off the tires. Comes off more easily when it's hot. Has been done for years in many racing series.

Particularly useful for getting accurate wear measurements. In the picture posted earlier in the thread you can see the wear indicators across the face of the tread and looks like the guy is writing down a worn number as well.

[marcush.]

ha jt -that does make sense only if you wrote down the original depth of the marks when the tyre was new...I did this on the Pirelli stuff in my Ferrari Challenge days and quickly realised each (tyre and wear indicator)has its own depth ... so you could get easily confused alerted and all measuring the wear indicators.I assume the F1 tyres are more precise?

[Jersey Tom]

I assume the F1 tyres are more precise?

I wouldn't make that assumption.

[marcush.]

it was my try at being funny...excuse me ,I´m german...

on a morre serious note ,I was asking myself when doing this rather boring work if it was not actually hurting tyre life to heat up the tyre in an uncontrolled way locally ..Any thought on this?

[Giblet]

A friend of mine told me that in some series, street tires are 'lathed' and the tread cut down to make them 'slicks'.

[marcush.]

A friend of mine told me that in some series, street tires are 'lathed' and the tread cut down to make them 'slicks'.

did that in historic racing.We had to use a spec tyre and you just tore out the thread blocks when using new tyres .Reducing thread depth on brand new tyres adressed this problem very well and on top of it you had much increased footprint and lower tyre temps -in effect the tyre lasted longer even when starting with half the thread ...
We had someobne grind the tyres down on a special machine in a nearby tyre manufacturing plant .

[strad]

A friend of mine told me that in some series, street tires are 'lathed' and the tread cut down to make them 'slicks'

Giblet;
I think you are referring to the fact that in many series where they use treaded tires the tread is thick (depth of tread) enough that a driver can feel the tire squirm when pushing to racing extremes. So the take off about half the tread to make the tire more stable.
You can feel it when you buy a new set for your road car..

[marcush.]

the new tyre is literally torn apart .taking away much of the original tread thickness lowers tyre temps and makes the tyre a lot sitiffer

[Giblet]

No it was definitely shaving a tire down to make them perform better.

I am drawing a blank on the series name. I found this though:

http://blog.tirerack.com/blog/chads-742 ... tition-use

And it looks like they shave them down to give a bigger contact patch and reduce weight and chatter on the tires.

Tire shaving will allow a wider contact patch vs. a tire "wore down"
Tire shaving reduces tire weight by a few pounds
Tire shaving will reduce tire squirm, allowing better tire response and corner handling
Tire shaving will reduce heat build up
Tire shaving will allow a tire to last longer in competition vs a non-shaved tire.

[strad]

No it was definitely shaving a tire down to make them perform better.

I am drawing a blank on the series name. I found this though:

Giblet...They do it in many series that require treaded/street tires just as I told you above. They do not make them into slicks as that would violate the rules.

Tire shaving is an effective means of permitting more of a tire's performance capability to be realized early in its life. Tire shaving removes tread rubber and reduces tire weight by several pounds. A shaved tire's tread profile will usually result in a slight increase in the width of the tire's contact patch putting a little more rubber on the road. The resulting shallower tread depths reduce the tire's slip angle, increases its responsiveness and help stabilize its cornering power by minimizing tread block squirm. Minimizing tread block squirm also reduces heat buildup and the risk of making the tire go "off" by overheating its tread compound. And in many cases, shaved tires used in competition actually have a longer useful life than tires that begin being run at full tread depth.

So with all of these benefits, the next important question is: "How far should a tire be shaved?"

Hoosier R3S03, A3S03, R3S04 and A3S04 radials, as well as KUMHO ECSTA V710 tires are manufactured with 4/32 to 4.5/32" of molded tread depth and do not require tire shaving.

Most other DOT-legal Competition tires begin with about 6/32" of molded tread depth. While some tires do not require shaving for dry autocross use, all of them will benefit from shaving to about 4/32" tread depths for driver's schools, track days and competitive track use in dry conditions.

[Giblet]

Sorry Strad, I caught that but forget to acknowledge it. That was why I changed my wording to 'perform better'

Thanks.

[marcush.]

so we agree ,right?
some call it lathing ,i call it grinding and Demon tweeks calls it shaving ,i remember in the 80s? Pirelli supplied a peeling service to their clients for qualy tyres ...