Disk images in TAR format (Unix standard tape archive) can be probably converted to other disk image formats, such as the CloneCD format (.img) for burning purposes or to act as virtual installation media. This can be done with some of the disk conversion utilities that support both formats.
Convert Unix standard Archive format, Tape Archive to CloneCD image file.
We have found one software suitable in our database for this conversion.
Apple macOS / Mac OS X software - convert tar to img on OS X
A program for creating Mac OS X disk images
Convert from tar file format
The table with program actions contains information about what each program is capable of doing with their files. This may be a good pointer for further searches for certain file conversions and help you find the converter you are looking for if our search result is insufficient for you. However, it is far from perfect and may sometimes show results which are not really usable because of the nature of the software handles the files. So a conversion that appears as possible, just because of matched actions, may in fact not be possible.