Mercedes's car is due to be given its track debut on the short international version of the circuit, with Hamilton and his team-mate George Russell both making brief appearances on what is classed as a 15km demo day.
The first proper running will be in the form of a 200km filming day in Bahrain on Tuesday, on the eve of the start of official testing.
This year's car is hugely significant for the Brackley team after two disappointing years since the start of the current high downforce regulations era in 2022.
The W13 struggled badly with bouncing and porpoising, and while Russell scored a victory at Interlagos, the team slipped to third in the constructors' championship.
Last year's W14 did not represent the hope for step and underwent a major revamp after just a few races.
It failed to log a win in a season dominated by Red Bull and the team scored fewer points than the previous year, although it did move ahead of Ferrari to claim second in the championship.
The team underwent a restructuring in April, with Mike Elliott moving to the role of chief technical officer and James Allison swapping roles and returning to frontline action as technical director. Elliott subsequently left the team in October.
The W15 is thus the first car designed and developed on Allison's watch, and it represents a major change from its predecessor as the team attempts to close the gap to pacesetters Red Bull.
"We're changing the concept," team principal Toto Wolff noted recently. "We're completely moving away from how we laid out the chassis, the weight distribution, the airflow.
"Literally there's almost every component being changed because only by doing that, I think we have a chance.
"We could get it wrong also. So between not gaining what we expect, to catching up and making a big step, and competing at the front, anything is possible."
McLaren is also giving its new MCL38 its maiden run at Silverstone on Wednesday, although the teams are using different versions of the track.
