I don't know exactly the tire percentage, but the btcc for example in croft the first two races are 18 laps and they used soft tires, in fact from qualifying to race there is only a second difference, I imagine because of the weight of the fuel, the record is the Same for the classification, although not everyone used the same compound, in short, Gooyear tires must last something because nobody stops to change wheels
1st race 18 laps: 1:21.468/1:22.498
2nd race 18 laps: 1:21.468/1:21.965
3rd race 15 laps: 1:21.468/1:22.165
the 3rd race was 15 laps and they did practically the same times