Straightening/flattening rubber treads?

Tape them to a board and gently heat them with a hair dryer.   Just be careful not to melt them,

You can also attach them to a board or some other item and dip them in boiling water.  Usually though, they will straighten out once applied to the model under a bit of tension.

You're better off buying single link tracks anyway. These T34 tracks from Tamiya are pretty cruddy. I think it's the ones in theT34-85 that have no detail on the insides?

I just finished an old Academy Wirbelwind with warped tracks. I hung them with a clamp on the bottom for weight, in front of a desk lamp for heat. After about a week of hanging with the light on for maybe an hour a night, they are straightened.

Thank you.