7.50's are a half inch wider across the tread than 7.00's.
They SHOULD (and I am not positive on this) be the same diameter/circumference as the 7.00's.
If the diameter is different, they may be a heavier ply (ie 8 ply vs 4 ply) or the old ones may have just been worn down that much. Do you have ply ratings on both sets?
To become schooled in tire sizes, I used
this website .
I hope this was helpful.
