HELP, Need Thick profile tires on 18x12 rims???

[70Firbird]

Do these even exist? the closest I found were the Mickey thompsons that were 30x 12.00x 18. The height is perfect, but I think they will be too narrow for a 12 inch wheel. Does anyone know of a tire that is 30 x 13.5-14 x 18? I'm really in a bind, can't seem to find any company that makes these.

Thanks guys!