The durometer reading is practically useless unless temps of the tires are recorded for that reading.
Age and temperature affect the reading the most.
A new tsl in the sun reads softer than a red in the shade.
Just pointing out, to truly compare, temps should be equal between different tires.
On the same day, same location, all tires in direct sun.
Less than a year old 39" reds were 63-65 durometer.
42" treps were 55-58.
37" reds were 64-65
42" tsls were 68-70.
The reading varies from lug to lug, you need to get an average.
Tsls in the shade are 71-72 if they are newer. 9 yr old ones are 77-79.
Old 42" iroks were 75 in the sun, 77 in the shade.
Brand new Reds in the shade are 73.
Brand new Nitto 40" dot Trail grapplers were 78 in the shade.
5 year old Maxxis 38" dot creepys were 75 in the shade.
All were taken with an air temp around 80- 82 degrees.