[Daschicken]

I'm going to say it probably wouldn't be worth it. I really doubt you would drive the trailer enough to break even, or wear out either set of tires. As herektir said above, trailer tires usually have a low speed rating, something like 80 mph, if that. I wouldn't feel comfortable operating a tire close to the speed rating for longer than an hour. Personally I would stick to 65 mph max speed for towing with medium-large sized trailer tires. Small trailer tires I wouldn't want to go faster than 55 mph. Inflate your tires at the max cold pressure before trips, if stored inside, keep them away from electric motors(fridges) as they emit ozone that can damage the tires. If stored outside, keep them covered so the sun won't damage them as quickly.

Wait until the tires are ready for replacement before you consider something like this. Also consider that trailer tires are specifically built with very stiff sidewalls so they have less sway. If you don't like sway, don't even consider stepping down to a passenger car tire. LT(light truck) tires have stiffer sidewalls, but trailer tires are stiffer still.