Called ‘Alien Stompers’ by Reebok, these were made as hi-tops (Ripley) and low-tops (Bishop) for the film, and mass-produced as low-tops as a tie-in in 1986. They were recently mass-produced in extremely limited numbers in 2016 in both versions to commemorate the 30th anniversary of the film.
Retouched screencaps below the jump:
Note that Ripley’s top straps are substantially shorter than the production versions, as measured by space to the free end of the strap from the edge of the “Reebok” wordmark. They appear to have been deliberately cut shorter, as the end of the strap is not rounded nor sewn. This is most visible in the picture above with the flare (top right).
Below is what appears to be a contemporaneous promo poster:
Retouched sneakers crop: