That is the size of the tires on herself’s van.  I have four 255.65.R16 tires which I thought I could use for her van. With a small difference I thought it would be safe to use.

I was wrong. New computerized vehicles rely on tire revolution for many of the critical factors of the vehicle operation. After plugging the numbers in to a tire compatibility program it was determined that the snow tires would register 50 yards more in a mile and computer would not be happy. This is sufficient to cause the vehicle to perform poorly. 
Just another reason to be irritated by motor vehicle computers.