Tyre Wear and Lap Times.

[tok-tokkie]

I am confused as to why the lap times have been steadily increasing during testing as the tyres wear. Here are 2 graphs from http://abulafiaf1.wordpress.com/. Abulafiaf1 is a member here.


Graph from 27 February posting. This graph of Kobayashi (dark, Sauber) and Maldonado (light, Williams) clearly shows the lap times increasing each lap.


Graph from 1 March posting. This graph shows 3 last year lap times: Schumacher (black), Vettel (blue) & Hamilton (yellow) against Rosberg (red) at the Barcelona test. Clearly last year the tyres were pretty consistent as they wore down (but were said to ‘fall off the cliff’ once completely worn). (Note, Rosberg’s lap times have been adjusted to compensate for the colder temperature but the change each lap is not affected by that.)

On a slick tyre I can’t understand why there would be steady lap time increase as the tyre wears – a flat surface of the same rubber is being used all the time. The fuel load is decreasing each lap which makes the car go faster. Any explanation (Jersy Tom)?

[spacer]

I can’t understand why there would be steady lap time increase as the tyre wears – a flat surface of the same rubber is being used all the time.

As far as my limited knowledge goes, this is where you're wrong. It ain't the same rubber anymore once you've abused it around a racetrack for a bunch of laps.

[raymondu999]

Yup there's probably heat deg going through the tyre too - if it was just the rubber running out then the laptimes would just go down (quicker)

[Jersey Tom]

Most of the stuff alluded to here is on point.

Tire carcass changes as it gets deflected and stretched and pulled every lap... rubber evolves similarly with strain and heat... and as you wear rubber off you change your running temperature as well.

And it doesn't have to change much for your pace to be junk. On a 1:30 lap, to gain or lose a tenth of a second is only a 0.1% change. A whole percent is about one second.