Yes you can: there are a range of formulated dye products - such
as spray cans - which can be used to either change or enhance the
tan/colour of shoes and boots. On the whole dyes are designed to
enhance old leather, and give it new life; although they can play
a role in transforming a shoe which is in an old unfashionable colour.
What should be noted with many dye products, is that the original
colour of the leather will impact upon the result of the dye. Most
dye products are not capable of changing a dark leather to a light
leather colour; although some dyes claim to be able to change black
leather to white leather. To ensure that the dye will not crack
or chip, it is best to apply at least two coats of dye.