You haven't indicated just what your current tires are but based on what little info you did provide I'd guess you're currently running ST205/75 R14 LR C tires. If upgrading to Goodyear Endurance tires they would be ST205/75 R14 LR D tires which are to be cold inflated up to 65 p.s.i. Some with lighter trailers would argue it's not necessary to inflate fully to this pressure but others, myself included, do run ours @ 65 p.s.i. regardless. Others may also disagree but with this size especially I wouldn't have any concern at all as to whether the stock rims that used to carry LR C / 50 p.s.i. tires can handle LR D / 65 p.s.i. tires ... your concern is much ado about nothing. JMO. :)