you did a lot of work for make a correct tyre balance, but to me the race strategy is boring because after 1 or 2 seasons is always the same. If a race is a little more unpredictable is also more funny imho.
Suggestion:
secret and random tyre wear and tyre performance every season within a range of values
Pre season test in the same simulator of the race(to be decided how many laps (100? 200?) every players can run and if 1 or 2 or more truck in which do test)
This test allow players to have every season different from the previous one and less boring strategy (boring because always the same)
The tyre balancing become unnecessary because every season the players have to discover themselves which are best tyres, best strategy
Sorry for my bad english i hope you understand