I didn't measure anything. I was looking at tire specs online. Supposedly, my spare is 25.52 inches in diameter and my rear tires spec at 25.68 inches. I want to eventually put a limited-slip in my car, and wonder if I ever got a flat, would the difference of the spare diameter cause damage to the clutches.
the tire specs. are not always what is implied. it depends on the brand and what size rim they are installed on. (actual size may vary). I had 4 tires (same advertised size) , 3 different brands and they were 3 different physical sizes...
...... I had a car aligned once, it still wouldn't track right. I took it back and told the Guy at the shop. what he did was pull all the wheels off the car and lined them up side by side. they were the same size tires just 3 different brands, they looked like a set of steps...