Trailer has sat awhile, should I be scared about my tires?

also how and where was the trailer stored?
if bad dranage gravel, dirt grass, etc the tires can dry rot. ( in one storage season) inspect before every trip.
no need to wreck your rig do to a bad tire.
most trailer made tires can do good for 5 years no problem. but best if in a place they do not sit in water hole, and are shaded from the sun.
read the dot numbers it is a code for date of manf,
no reason to "oil" a tire does no good other than making your wallet lighter.

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