I'm in the process of getting some new wheels.
The ones I'm looking at are 20x9.5.
So my question is would a 245/40r20 fit a 9.5 wheel?

 

search for the spec of the tires you are going to be using. it will give the minimum, optimal and maximum wheel widths. a quick search showed one brand of a 245 wide tire having a max wheel width of 9.5 so it would probably be ok