So I bit the bullet and finally did this in September. I took the trailer into discount tire (I need two new tires anyway!). They sold me 5 16" alloy rims (with the correct weight rating I needed) and 5 brand truck tires (I forget the brand now). I was all in for $1000 from the dealer (they had some specials going on because it was memorial day coming up). I took the old wheels home and sold them on craigslist for $200. Not a bad upgrade for $800 in the end. My friends have done similar things with their trailers and they are running the same tires for 5-6 seasons rather than 2-3. Truck tires are not much more expensive than the crappy trailer tires either! I can be confident my tires/wheels are not the weakest link. My trailer is a 2008 SL3005 and has the axles flipped. She sits really high now! The previous owner had had a 3 step installed, so I have no entry/exit issues.