Tuchel is impressed with the impact the 34-year-old has had on the team so far since taking over as Chelsea head coach last month.
Giroud has not been one of the first names on Chelsea team sheet but has always delivered when called upon.
The France international has scored eleven goals in ten starts for the West Londoners in all competitions this season.
Ahead of Chelsea’s Premier League match against Manchester United on Sunday, Tuchel says Giroud "deserves to start all the time" but will not confirm whether the French striker will face Ole Gunnar Solskjaer’s men from the first minute.
"He [Giroud] deserves to start all the time," said the former Borussia Dortmund and Paris Saint-Germain coach.
"He trains very well and he is a leader in the group with a big personality, even when he doesn't start. But I will not tell you now if he will play from the first minute."
The German coach is likely to come up against Edinson Cavani, who he managed at Parc des Prince.
The Chelsea boss says both Cavani and Giroud are "top class strikers", despite both being aged 34.
"When they swap shirts you know how fit they are," said Tuchel.
"Oli [Giroud] is 100% fit with zero body fat and it's the same with Edi [Cavani]. As a number nine he is always concerned about the team and to sacrifice and defend.
"This is the characteristic of them both and they are both excellent finishers in the box. Both are top quality strikers and their fitness and self-discipline is key to their success."
Meanwhile defender Thiago Silva remains the only player sidelined through injury.
"He did an individual session today but it was on the pitch and felt it was big step forward," added Tuchel.
"I hope he will join the group next week."
