Leather, Thick jackets, Denim may take a few chomps.
I dont think its at cut and dry as just biting through. i mean they would not have to bite through it to hurt you, they could do alot of damage just with the pressure of their undead jaws!!
So i would look for something that like a leather jacket but ensuring it was padded, something like a biker jacket with the armor built in.
or possibly BMX armor with a jacket over the top etc