It depends on the trailer what I'm going to say
When I got my first Trailer my daughter was still in diapers (it was a Popup) one of the tires was a 16 ply I think and tossed the tread (must have been a re-cap) I kept it as a spare and the last time I used it .. My daughter had graduated college with a Bachelor's in Music and another in Education.
That was a very lightweight trailer and on one occasion (the last time I used the spare in fact) the tire blew and I did not even know it... The trailer towed the same with the flat.
I did not worry so much with that one.
With my Class A.... I WORRY.