Your asking someone to buy new ST tires at say $150 a pop for $600 for a one and done project..
The tires on that unit appear to be "mobile home" tires on open mobile home rims. They are not cheap and getting the correct size to fit those rims is often not an easy task. And now days with all of these shortages could be substantially much more expensive than $600.
As long as the trailer is not loaded to the ceiling and the driver keeps the speed low and the tires are not showing big gapping holes and holding air they WILL most likely survive low speed turning for the 20 miles that was mentioned.
Mobile home movers do this ALL the time with old tires and often on mobile homes that sat in place for well over 40yrs.
The mobile home that was on my property was a 1960s', placed on the property sometime in late 1970's, I bought property early 1990's.. So, if you follow the math the tires on the mobile home I had to make go away were in the range of 30yrs old. All I did was put some air in them and they survived a trip down the road about 10 miles..
Mobile Home mover didn't even blink an eye at those tires..
Now if the route was on a 70MPH Interstate, that would be a hole nuther can o worms to deal with since most states frown on driving too far under the speed limit.
Good point on house trailer wheels. However....
The tires are going on a two hour trip which doesn't tell us how many miles and at what speeds.
The tires are junk and in my opinion won't make a two hour trip at any speed.
WE have no idea of the tires actual age as many mobilehome movers will buy and sell old 14.5" tires/axles/wheels to a trailer owner that is transporting the trailer himself.
The OP says the person doing the moving says to make sure the tires are good.
In the '60s/'70s I had my own mobilehome/camping trailers repair business. We moved and up righted wrecked or storm blow overs back to our shop for R&R. Old (age) 14.5" trailer tires that sat flat like the picture shows for very long are junk and never made it 15-20 miles back to the shop on county roads at slow speeds.
The OP is still going to need tires.
If their 14.5" then many mobilhome movers in that area will be a good place for those size used tires.
The person doing the moving will have some say about how the tires look and willing to take a chance.