j4kwan wrote:
then really this means you have to figure tyre selection and car setup selection simultaneously, right?
If you mean during a tyre test session, no. On a tyre test day you test tyre only, because you need to minimize the number of variables so they use a standard reference setup, standard aero, standard engine characteristics etc etc, they try to keep everything else equal changing only the tyre specifications. That’s why teams complain about tyre testing, it takes lot of time, require to produce lot of parts and you can’t develop the car.
I’ve been to several test days and did talk with a few guys from teams (particularly of Ferrari since they come here more often than others) and here a description of what typically happens (assuming tyre changes in race are allowed)
At the start of the session the driver makes a couple of laps with a reference, well known, tyre specification to verify that with the track condition the reference setup on the car gives the expected results, if necessary they make couple of modifications and a few laps more to have a well definite reference.
Then the real tyre testing starts, they put on a given specification, driver make a stint of few laps (6-7) and then stop few minutes, no work on the car (beside refuelling if necessary), and back on the track with a different tyre specification, same number of laps, stop, change tyres and loop... If required for example in the middle of the session, they possibly make a couple of laps with the reference tyre specification (same used before starting the test) to verify the influence of possible changes in track conditions.
A short stint of just 6 or 7 laps is more than enough to evaluate a tyre specification because, with tyre change allowed, they are mainly interested in the performance drop, not in tyre durability (that’s not really an issue in a 100 km stint). After just few laps the rate of performance drop becomes easily predictable hence with a 6-7 laps stint they can evaluate with enough accuracy how a tyre set would behave for a 20-22 laps stint. That’s good for a first selection when you have big differences between the specifications, once the tyre general characteristics are set and you are working on small refinements then it becomes useful to make longer stints.
Things were lot more difficult in 2005 with the single set per race rule because teams where interested in durability, hence tyre “consumption”, and that you can’t model/evaluate as easily as performance drop, so if a tyre specification has to last 300 km, you have to test it for at least 260-270 km, shorter distance would be useless.
Obviously 270 km require lot of time, I’ve seen tyre testing in 2005 with Ferrari, Badoer, using the same tyre set for the whole morning (with separate stints of 16-17 laps) while previous years it was normal to evaluate 5-6 different specifications in the same timeframe.
This obviously makes it harder to find the right specification and also makes more difficult the evaluation because the longer it takes to test a single specifications the more variables you add, track conditions can change more; then you can test just one tyre set per specifications, hence with the risk of trashing a specification that was potentially good because there was a manufacturing problem in that specific set; that’s a rare event because the “test” tyres receive an higher level of attention on manufacturing compared with the “normal” production for gp, but it can happen.
