Converting to shapefiles that have street widths?

We have some shapefiles that were converted from OSM and are using stylesheets to give the streets width (without stylesheets the render as a single line centered on the street). Problem is they’re rendering too slowly with our graphics engine. They’d render much faster if they were tesselated polygons or some other geometry. Is there a converter from OSM to shapefile or possibly shapefile to shapefile that adds geometric widths to roads?

There is a proposal to map street areas. See

You could use a standard geo buffer operation, such as st_buffer. You’ll need to do it in a sensible projection (not wgs84, but you might get away with Popular Mercator). The problem might be how buffering changes the shape of roads, especially at their ends. Even lacking road widths it is possible to make sensible assumptions about the widths of individual classes of roads.