Just ordered me a set of 275/60/20 Coopers which are supposed to be 33 inch tires. Just measured my stockers which currently have 33,000 miles on them and they measure right at 30 1/2 inches. They are 275/65/18 which are supposed to measure 32 inches. I was only expecting a 1/2 difference in overall height but based on this info I am going to end up with an inch and a quarter which I consider to be significant. Just added a 2" AS kit which definitely made a difference. Does all this make sense? Is the lost tread on the stockers where I lost the inch and a half?

 

How did you measure the tire? Tires are measured by the factories without being mounted on a vehicle because the weight of a truck will compress the sidewall.