It all depends on the tire you will use on it. It is a wrong belief, as I am just getting to know now, that the rim width should be the same as the tire width. A search on the net and I found the following info..
"The wheel width or rim width is the distance between the outside edges of the bead seat. Most popular rim width for 4x4s would be 6", 7", 7.5", 8" and 10". Rims wider than this are usually only used on trucks with extreme overwidth tires. The tire manufacturer will publish guidelines for what rim width should be used with which tire. In general 7" rims will comfortably work with tires up to 10.5" wide, 8" wide rims work for 9.5" up to 12.5" wide tires and 10" wide rims are used for 12.5" and wider. Many rims will not be available in width wider than 8" and rims wider than 10" are much more difficult to find."