By "split", do you mean across the bottom of a flat tire? (That'd be the worst case).
Trailer tires are notorious for cracking and failing. Rubber tires should be "exercised"; if not, at least stored off the ground and unloaded. (Even new, and unmounted).
The only risk
I'd take with questionable tires would be the trip to replace them!
I've always gone to a Wolfeboro gas station and purchased used
passenger car tires. The date of manufacture is molded into the sidewall. Pick through them for size and recent manufacture. Some are very recent "takeoffs" due to issues unrelated to trailer use. (Comfort, noise). With only a 2-mile "commute", even a minor vibration complaint wouldn't be a problem.
A neighbor asked my opinion on a trailer tire he'd just removed. The sidewalls looked fine until I pressed down on the sidewall with my shoe and was astonished how totally-cracked ithe sidewall was.
As for bias-ply versus radial, both are used in auto racing.
As above, I'd buy American, although Carlisle isn't the best. The Carlisle "brand" is shared with many other inexpensive "makes", sold by Costco, Wal-Mart, and Sears.
Firestone, for example, sells "Cooper", made by Carlisle.
"Pioneer" is made in China.
More, and consistent, views:
https://www.winnipesaukee.com/forums...ight=exercised