JIM,
I built it out of some really crooked maple beams i found at the lumber company,i work at,and some 1inch pt.yes it does support the 23,although it does flex a bit.you can build one using 2by 12s cut "rounded" you will get the same effect..double them up for strength,and keep the beams under the tires.i usually cross on the rocks in the summer,but use the bridge in the winter,because this is where i cross with the snowblower.the other bridge on the right is a 6by 12 we use as a footpath to get to our pool.HERES A GOOD ANGLE OF THE BRIDGE
ESCAVADER