Radials seem to ride lower than bias ply. They always look like they're under-inflated. Does this have an effect on car height? Should it be factored in when figuring what size in today's terms would match an old 7.60/15 or an 8.50/14, etc.? Would it affect the speedometer, or do radials "grow" at highway speeds, like the slicks on a top fueler? Dumb questions? George Clineman