Did you notice your front sidewall is a tad shorter than your rears even though they're the same 40 series? Looks like about a 1/4" difference between the top of the numbers and the line above them. So maybe a 1/2" difference in overall height?
Just incase there is any confusion.....
Example: P215/70R15
215= tread width in MM (different manufacturer's measure how wide a tire is in different parts of the tread/sidewall)
P= Pmetric.... LT= light truck and normally 6,8 or 10 ply (C,D or E load range)....
70= 70% as tall as it is wide....40 = 40% as tall as it is wide.....
15 = the big hole in the middle... lol (don't think that needs explaining)..
Now a 31X10.5R15 is totally different...
31= how tall the tire is ( diameter) meaning 31 inches tall (wheel with will effect how tall a tire is....
10.5= how wide the tire is, 10.5 inches wide..... R= radial (steel belted construction)....
15= big hole in middle on tire.....
ST205/75R15 is a trailer tire..
ST205/75D15 is a trailer tire also..
R = Radial construction
D= Bias Ply construction.
Now on a trailer tire right after the 15 (or whatever size you have) C,D or E is the load range (plys)...
If there is a XL in the tire size description then said tire has an extra load range......
PS: on trailer tires how the suspension is set up affects what construction of tire...
Radial is for sprung axles
D- Bias Ply is for hard mount axles