In Reply to: Treadwear numbers? posted by Anthony 88 ///M3 on October 22, 2001 at 12:23:25:
They have this place in Texas somewhere with a course...roads, hwy, etc. The "average" number of laps, miles, or whatever that a tire will last (not sure of the definition of worn out though) gives a 100 treadwear rating, meaning 100% of the "standard."
So, with new tires, they send them out to this DOT testing place and test them out. They stick them on the standard car and drive the couse until they wear out. The number they get is how long they lasted. 300 means the tire went 300% of the standard distance. 180 means, you guessed it, 180%. I don't know when they came up with the standard but you never see 100 or below. Most sticky Z-rated tires are 180.
I think I read this in a tire article in one of the car mags I subscribe to.
Can someone please explain what they mean?