I dont want to get the argument started again, you can read it on another thread if you have doubts. Does it make sense to you to pick up any vehicle by the frame to remove and replace a single tire as opposed to lifting the axle 1.5 inches to remove and replace a tire? What will you do on the road? Will you have a giant jack handy to lift your trailer or will you simply use a jack, probably your TV jack to gently lift the axle a replace the tire? IF I were to apply jack to my frame to lift it, it would not be at a single point but rather several jacks along the entire side to reduce the risk of torquing the frame of my trailer.
That having been said, $1500 is not bad, mounted and balanced. perhaps they will give you a deep discount if you buy 5. Another way to get a set of 614 is to buy them from a online tire dealer, (normally no sales tax but freight instead) then have them mounted and balanced at a tire shop somewhere, might save a 100 to 150 bucks. I dont know if I would go online to same that little bit of money or not, but hey, $100 buck is a 100 buck to the very frugal. You seem to be frugal or you would not be thinking of the 614. They are a good buy but more expensive on the onset.
But to answer your question, if you do let the tire company lift the axle, just make sure they lift it under the axle at the spring or real close to that point. You can bend or crush the axle tube if you are careless, it is not likely that an experienced tire dealer is going to harm your rig installing a tire. Just tell them outright that you are concerned about it, If he is professional he will note your concern and address it for you. If you have a level up system then you can pick it up for him. I used my TV jack, on the axle tube next to the spring and did not even put a mark on the paint. So decide for yourself if this rates this level of scrutiny for such a simple task. Jacking up a trailer axle has been the most common procedure to change a tire on trailers than any other procedure. There are a lot of trailer axles and wheels out on the road, and I doubt that you can find very many who will tell you that they ruined their axle changing a tire, or who have ever heard that you are supposed to jack up the frame.
We have a new-to-us (this year) 2010 Bighorn 3610RE. It currently has Freestar LT235/85/R16 tires. There's heaps about Towmax tires but not much on Freestar, though I believe these are the original tires. The born-on date doesn't correspond with the DOT codes since the last four digits which are usually week and year. When I went to look at tires on the other side, there was only a the 1st four digits, so apparently they are on backwards? (Meaning the outside is on the inside). Does that even matter? (Sorry, probably a stupid rookie question, but I'd still like to know). We are about to set off on full-time expedition so we are thinking of replacing the tires regardless since I saw some cracks on the sidewall and since we don't know how tires were cared for (proper pressure, excess speed, etc)... Getting estimate of +/- $1500 for 4 Goodyear G614. Goodyear said they could replace the tires. There was also another thread/discussion of where to put the jack (with a photo of a 5th wheel on jacks outside what looked like a tire shop). Is this something the shop wouldn't know???