I also have the blackwaters. I have them in 28-10-12 at all corners plus a spare. Mine measure true 28", within 1/4", I am not sure how other people are measuring their tires, but you don't measure the height of the tire after it is mounted to the vehicle. If you do that, it will not measure the true height, as it is compressing under the weight of the vehicle. Either way, they are good tires, heavy, but good. There was a significant performance hit with mine, but then I went to 28", so maybe with 27" it's not as noticeable.