I rode on 23s for a long time and was over 350 lbs when I started. 25s are quite a bit more comfortable for me though - I was surprised how much difference 2mm in width makes in ride comfort. You should probably start saving for some big boy wheels. At 230+, you'll probably want 36 spokes on the rear and 32 front. Ride the stock wheels until you start having spoke/truing issues though.