The tire size is a fairly common question across Pathy forums. The biggest issue for our R50's is the front strut clearance. Generally, I agree with yellowbug. 30" is about as much as you're going to get away with before you run into clearance issues at the strut.
Regarding wheel width, check your tire mfg's page. They should have a fit guide that says what wheel width the tire will accommodate. For example, I have Firestone destination AT's at 265/75 R16 (31"). My Pathy has a 2" lift and stock wheels. Firestone website says that the tires can fit wheels from 7-9". Here's a link to the Destination AT chart:
http://www.firestonetire.com/productdet ... nation_a/t.
When these tires went on new, they did rub at the strut, but not enough to be worried. They just made noise for the first 100+ miles.
Lastly, I think the stock wheel backspace is 4" for 2000-2004 Pathys. Mine is on '04 and is 4", and I'm fairly sure that the one's you've got pictured are too. I'm not positive about the 99.5-01 five-spoke wheels.
If you want larger tires w/o lifting, you can get wheels that have smaller negative backspacing (go from 4" to 3.5" BS) or spacers to pull away from the strut. Yes, that brings other things into play, but those are the joys of modding!!
Hope this helps...