The Terai Tiger

[Pckts]

Track size can be dependent on many factors.
Old tracks will be more worn down compared to newer ones.
Erratic driving and passing leads to larger tracks and long or short grass surrounding the tracks will all play roles. 
Picking where one track begins and another ends is also flawed since all tracks are ran over time and time again so picking out tracks that belong to a single vehicle is impossible.

When it comes to eye witness accounts, I'll take them over a camera trap photo any day. Most people can tell which cats are larger unless they are close in size, mass is even easier to tell. Then when you're talking about people who've seen 100s in their lifetime,  their word holds even more weight. 
For instance

*This image is copyright of its original author

In regards to peole who've seen Sunderban and terai tigers, I'd be very skeptical of that claim. I've never seen anyone say they are the same size let alone half of all people who've seen both, Sunderban tigers are also very hard to spot and even harder to get close too, compared to terai Tigers which are far more known and seen closer much more often.

Lastly is this, watch videos of Tadoba Females next to jeeps compared to Kanha ones for instance, their size difference is easily noticeable. Look at muscle mass and head size of Kanha males compared to Tadoba males and you'll see the same. I only got to see a few of each but the size difference was noticeable for sure but I know quite a few who've seen many of the famous C. Indian Tigers and they say the same as well. The only park that I've ever heard of having comparably sized cats to Kanha in C. India is Bandhavgarh and even then its fewer than most who say it. 

There is definitely a difference in Cat physiology between parks, some are more pronounced than others but I have no doubt that certain parks will produce larger animals. I've seen it with my own eyes and you go to these parks and you can tell right away that some have more going for them than others. Reply