Solved

tyres / laps

how you calculate how many laps will take each tyres depending the % of degradation?

example i have 
SS= 13% 
S= 8% 
M=6% 
H=5% 

how you know with this % how many laps will arrived to 50% of use?

Divide 50 by the percentage wear per lap.  Round your answer down, I would say.  That will give you the number of laps that you should be able to do on pl3 that would give under 50% tyre degrigation.  
It is easiest to create a table of results for these ca0lculations, then you will not need to use a calculator, every time you would want to calculate these figures.

There aren’t any proper formula to calculate it?
Due that if I divide 50 it’s not real, due that the tyres degradation is not lineal 

For SS:


100 - 13% = 87
87 - 13% = 75.69
75.69 - 13% = 65.85
65.85 - 13% = 57.28
57.28 - 13% = 49.84

And so on..

Same applies with the other tyres. That's why you don't see a "linear" degradation. You should always take the 13% away from what's left of your tyre and not the 13 as a number:

100 - 13 = 87
87 - 13 = 74
74 - 13 = 61
61 - 13 = 48

This last one is wrong. Tells you can only run 4 laps until "50%" but you can actually run 5 as you can see from the first example.

Thanks a lot