I have just always wondered if the tune you can download off the leaderboard from people is the same one they set their time with?
Although it can be unbelievable sometimes, it is the tune used. The only way to link a tune with a lap is to use that tune. The tune can be shared after placing the lap and unless the name is altered or the tune is resaved in general, the tune will be linked to the lap.
If the bug is still in the game then no, it is not always the same tune. I have recognized, as i had a shared tune on my car while i decided to upgrade it in the next higher class without changing anything in the tune, the LB showed a shared tune. So if you would have choosen to download the tune from the LB, which was A-Class, you then got a B-Class tune. Don’t know if this is still the same problem as the thread in the support section got closed and removed without any answer.