Hi Keith,
Thanks for writing in.
Sounds like the stimulus is definitely ME (not Maximal/Strength or Capacity). ME should be specific to the event you’re training for. Sounds like the tire drags simulate going uphill with and without boots, weight and snow. So, if you are facing forward for these drags than you’re achieving as much of the specificity as you can without the potentially harmful downhill action that would otherwise happen if you were going uphill.
Forward step-down from a low (6-8inch) box might help the knees and give you controlled stimulus missing from not descending, if you’re looking for that stimulus.
-Seth