Rex tend to be more prone to sore hock issues. Though the wire floor could be contributing, hard flooring and carpeting when rabbits are let out to play, can also play a big part. Carpeting can be really rough on their feet, and hard flooring causes rabbits to shift their body weight back onto their hocks more, increasing the pressure and rubbing on the heal.
Key is managing the flooring surface as much as possible. Fleece, sherpa fleece, and the foam tile mats can help a lot with managing sore hocks. Soft hay really is the best surface, but not often doable, especially for indoor buns. It's usually better not to be applying ointments or anything unless it has gotten to the point that the hocks are very sore and there are wounds that need treating(and then other measures also need to be taken), as the ointments will soften the skin and make then even more prone to soreness. But if there are open wounds or sores, then ointments(and possibly a vet visit and antibiotics) may be needed to help with healing, but this will also require covering the area to protect it and keep the ointment from being rubbed or licked off immediately. I know some owners have used baby socks to protect their buns feet, and vet wrap can be used, though needs to be used with caution and best used under vet advise, as wrapping it too tightly can be disastrous.
If my buns feet aren't bad, sore skin with no wounds, I've just changed flooring surfaces to fix the problem. If they are slightly bad with minor abrasions(no infection and no swelling), baby socks(if bun will tolerate) and some ointment to help the sore heal. If they are getting more severe and there may be a risk of infection and/or inflammation, you should take your bun to your vet. If in doubt of the severity, always best to consult your vet.
http://www.rabbitsonline.net/showthread.php?t=69718&page=2
http://www.bio.miami.edu/hare/sorehocks.html
http://www.medirabbit.com/EN/Skin_diseases/Mechanical/Pod/Podo.htm
