Wonder what they used for checking tire, I used a Durometer & even then numbers would vary between tires, new tires were softer than used. But even still number varied but were never lower than the new tires. I marked one tire w/ my grease marker, crew man I knew gave me some grief about it & wiped it off. Just harassing me, I went over used about half that grease marker on that tire. The mark went from the rim to the tread & about 6 inches at the top & 4 at the bottom, told him he gave any more guff he was outta here. He ended up getting that marker on his pants & stayed there till he threw them away. LOL