In the manual for my TC24D, it says the rears can be dished in or dished out to adjust the width, but with the wide turfs on my machine, the widest setting (dished in) is the only way they can be mounted. I tried switching them just out of curiosity, and it can't be done. So in my case, they were already set for a wider wheel base. If yours is not, give it a try. Other than fitting between trees or covering your tracks with a mower or blade, I can't imagine why you wouldn't want the wider setting for stability.
Brad