[1953M100]

Open trailered my '31 Coupe to a car show in Iowa a couple weeks ago. Headed down 35W interstate at 70mph until I noticed the soft top roof starting to "bulge" and "balloon" at anything above 60mph. Tried to keep my speed down to 55mph the rest of the way, but I don't like travelling 15mph below the speed limit on the freeway, forcing everyone to pass. Not safe. For the trip home I borrowed a few ratchet straps and some carboard to prevent the condition on the return trip, worked pretty well, but kind of a hassle to secure without causing damage. A fella at the car show mentioned there was a cover available for open trailer towing. Tried searching, not finding anything like he described (??). Any of y'all heard of this...?