Thiago Silva, 37, Cesar Azpilicueta, 32, and Kalidou Koulibaly, 31, started the Blues’s opening day 1-0 away win at Everton on Saturday in a match where they rarely looked comfortable.
Despite the win, Tuchel admitted that the age of his current defence is a concern and could undermine Chelsea’s ambitions this season.
“It is a lot of experience, it is maybe another of age, it is a lot of experience and they have their quality and they know what they are doing,” Tuchel told reporters on Merseyside.
“We also need to make sure we have a new generation to take over in the next years but the guys are strong that is why they are under contract and the guys have our trust.
“There needs to be [balance]. I think it is necessary. The game in general is very physical and demands a lot. This is the situation. We knew it before.
“Azpi is the legend that he is, Thiago is in the moment still very important to us and when we had the chance to sign Kalidou we did it because we believe that he has some years ahead of him. But in general it is the fact that like the goalkeeper and the double sixes are in their thirties, and that is just what it is.
“Pace is an issue and speed is an issue. In all signings, this is the demand of the game that you can play one on ones, that you can defend space if needed with high-speed runs.”
Fofana, 21, would be a good fit for Chelsea but Leicester don’t want to let him go lightly - asking for upwards of a world record £85million fee for a defender if they are to sell their young French star.
The Blues manager has hinted that he only needs one more player in the transfer window, namely a defender, but there is also a concern about the lack of attacking threat.
“Well, we were joking at half-time and saying maybe it is a typical Chelsea game we win 1-0 and Jorgi scored with a penalty,” he added. “It is what it is.
“I think Raheem [Sterling] will lift Kai [Havertz], Mason [Mount] and [Christian] Pulisic up. Our formation is a deep formation because the centre of the formation is in the three centre backs and the two No6s, so it is a deep formation in which you rely heavily on the two wing-backs.
“Today we played with Ben Chilwell who was not, for me, 100 per cent ready to start but the situation with Marcos Alonso [soon to leave for Barcelona] and the late signing of Marc Cucurella made it necessary that we took the risk.
“Reece [James] struggles also at the moment to have full, full fitness so on the right we didn’t have enough from the wing backs to create a bit more freedom for the inner players.”