Might be worth taking care when you buy one.
I bought a hard plastic one for my 265/75x16 BFG AT's several years ago but when I tried to fit it I found it didn't fit over the tyre very well. Luckily I was doing this outside the dealer so I went back in and they asked me what make of tyre I had fitted, I told them they were BFG's and they got another cover (also for 265/75x16) but this one had a sticker inside stating it was suitable for BFG's. Tried this one on and it was a perfect fit.