Typically, when the outside edges of a tire are showing wear its because the tires are under-inflated. The solution is to inflate the tires to the maximum pressure listed on the sidewall.
Now if the outside of tires have what looks like gouges are taken out of the rubber most likely it is broken suspension components or its a bent axle or spindle.
Unlike passenger vehicle tires, you always want to have trailer tires inflated to the maximum tire pressure for the best performance and wear.
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