How can I treat extremely dry skin on the tops of my toes?

Depends on... ...The cause, as usual. If it's due to the material (or dye) in your shoes, you may need a cortisone cream (and new shoes). In all probability it is not athlete's foot, which occurs in between toes, not on top. If it's just dry skin, other areas of your body should be dry too - so if it's localized to your toe tops, i'd suggest you see a dermatologist and get a diagnosis.
Moistirize. Am lactin or cerave are good otc products for that area.If howe er skin is thickened you may need stronger product to peel away callus .