No a road Roads don't usually don't change classification when it changes the speed limit. limit changes. The way should still have the highway=trunk but be tagged with `highway=trunk`, and you might want can also add a [`maxspeed=*`][1] tag to set the [maxspeed=*][1] tag according to specify the new speed limit. [1]: http://wiki.openstreetmap.org/wiki/Key:maxspeed

No a road usually don't change classification when it changes speed limit. The way should still have the highway=trunk but you might want to set the [maxspeed=*][1] tag according to the new speed limit. [1]: http://wiki.openstreetmap.org/wiki/Key:maxspeed