Sometimes it might be useful to know the current grip level on tracks (especially on MP servers). You can actually use the built-in "car physics app". In order to see it though, you will need to enable Dev Apps in assetto_corsa.ini file (typically under STEAM\steamapps\common\assettocorsa\system\cfg). It will be represented as DYN_TRK parameter and it's sub-unitary. e.g. DYN_TRK = 0.963 means of course a grip of 96.3% and so on. Here is a screenshot:
