Originally Posted by Heyman46
I don't mind the way it looks, I don't understand why it's bad for the tire.
The manufacturer will list a recommended wheel width range for every size tire they make. It's a safety & performance thing. How a tire wears & even the ability to hold a bead comes into play.
A 10.5" tire is almost always listed as being a approved for 7" - 9" wide wheel. Most commonly installed on an 8" wide wheel.
For example, BFG lists a 31x10.50R15 All-Terrain T/A KO as having an approved rim width of 7"/9" (min/max) - Source: BFG Specs