The 2025 GMC Sierra HD pickup is gearing up for more changes and updates, according to a recent report from gmauthority.com. Following a significant mid-cycle refresh introduced with the 2024 model year, akin to its Chevy Silverado HD counterpart, the Sierra HD is expected to undergo further enhancements. GM Authority, a trusted source for insider information, has revealed the tentative start of regular production (SORP) date for the 2025 Sierra HD – July 29th, 2024. While this date is subject to potential alterations as plans evolve, it provides an early glimpse into GM's production timeline for this new model year.