car39 said:My wife's 2005 Volvo S40 would do burnouts at stop lights with hardly any throttle pressure. Tires looked great, had less than 30,000 miles on them. Changed them, problem solved. I thing they were as hard as granite.
In one of the tire mags, they pointed out that the first 2 or 3 32nds of "wear" on a tire is actually evaporation, not mechanical wear/material loss. This is why tires seem to wear to halfway very rapidly, then sort of plateau. The rubber isn't wearing to that point, it is shrinking and hardening.
This also explains why new tires shaved to 3/32 have a lot more grip than tires worn to 3/32. And why tires that have 30k on them can be scary bad even if they have "lots of tread".
After reading that article, I throw away snow tires when they reach 7-8/32, and my life has been much better for it.
