Despite a huge outlay on players, including the near-£200million world-record fee for Neymar, the French club have never progressed beyond the quarter-finals.
Tuchel is the latest man trying to achieve what Unai Emery, Laurent Blanc and Carlo Ancelotti failed to do but the German denied it was the only thing which mattered as they were expected to win Ligue 1 with ease.
"No-one has told me this, in all the talks, I have to win this otherwise I didn't do my job right," Tuchel said.
"If anyone had told me (that) I wouldn't have signed the contract.
"If we judge ourselves only by the biggest goal in European football, the possibility of a big disappointment is high. Why should we do this?
"Sometimes I feel sorry for my team because I know the effort they put in. We play at home against defensive teams and we win and win and win.
"It is not because it is easy, it is because these guys show the hunger to win and win and win. It is a point of view (that Ligue 1 is easy) that does not help us within the club."
Tuchel returns to Anfield almost 18 months after a chastening experience as Borussia Dortmund boss.
His side led 4-2 with 24 minutes to go of their Europa League quarter-final second leg only for Liverpool to score three times in a dramatic last-minute finish.
It means the PSG boss is wary of a team which is now even better than the one he faced in April 2016.
"We did handle it quite well. We were leading 2-0 and 3-1 (on the night) and then an outstanding goal from (Philippe) Coutinho changed everything," Tuchel added.
"It was a last-second defeat, just a step from a semi-final. I was asked if it still hurts me. I have to say I am more grateful that I was part of it.
"At Anfield, you need a lot of experience and courage. You can never feel comfortable against Jurgen's (Klopp) teams.
"You can never never have one minute where you think, 'We have it under control'.
"Even if we have the ball it can happen that in 10 seconds they can be in front of your goal.
"We can never put our concentration down for one second, we can never feel like we have a moment of calmness and quietness here.
"I think they (the players) know that. If not, I will tell them and they will be aware of that."
It is for that reason, and taking into account Liverpool's run to the final last season and the five European Cups they have in their trophy cabinet, Tuchel considers his side only a Champions League challenger and not a finalist.
"It does not bring you one centimetre to a title if you talk about who is favourite and who is not," he said.
"It does not make sense to talk about what happens in the next year, we have a very complicated group.
"Every year you start new and in sports – if you want to go far – you have to get the experience you can to do a special thing. You catch the wave and you ride it.
"You see Liverpool have won five Champions League titles so they have experienced this and we are still working against this.
"For this we are a challenger in the Champions League and not one of the favourites.
"But I am pretty confident this type of game and opponent bring the best out of us."