They both use the same balls, the ones supplied by the home tram. if they run out of those or they becomne unusale, then they get some from the visiting team.
If ther patriots had any advantage from the ball being underinflated, then hte colts had the exact same asdvantage. By definition of htey both had it ,then neither had an advantage.
Now here;'s another hting to ask before the tin foil cuts of whatever circulatino is left to yuor head:
How did htey get under-inflated?
They were fully inflated and tested prior ot hte game and were found to be within spec.
Then the balls got wet. Really wet.
Those of us with an IQ not on the left side of the bell curve know what happens to leather when it gets wet.
For the rest of you, I'll elaborate (explain). And I'll type slowly.
When leather gets soaked in water, it teds to become softer, more compliant, and stretchable.
If leather was in tension and got soaked, eventually it would give and stretch and the AMOUNT OF TENSION WOULD BE REDUCED.
Either way, it does not matter because both terams played with the same balls. One tram played really well with those footballs, the other stunk up the entire city with therir lackluster performance.
If you really need an excuse to deal with that, get therapy.
From the O'fficial NFL.COM website:
NFL.com Rulebook