Attached Link: http://perso.club-internet.fr/lemog/lemog_textures/metal_toles.htm

I've made metal texture tests a while ago. Metal is generally not as smooth as the default Bryce ones. I would use a brushed pewter textures with a bitmap texture used as bump and maybe diffusion/diffuse color map. Also reduce reflexion if you want the Check out the attached site for tileable metal textures. I've had good results with these.