305/40r22s?

anyone think i will run into problems if i'm towing w/ this size tire (305/40r22). i figure the car & trailer will weight 4500-5000lbs. any insight?

You should be fine. My friend tows an enclosed with that tire size on an Avalanche with no problems.
The sidewall on that tire is still pretty big. Just get the tire with the highest load rating you can find.