I have not heard of this issue with speed rating, but I have had with load index. I tried to order some smartcar tires for my VW karmann ghia. They called me and cancelled the order because the tires would not handle the weight. I tried to explain I was only using up front, but they would not sell them to me. They explained that the weight must be handled by 2 tires (which makes sense if front and back, but pretty hard to pull a reverse wheelie. (boom06)