Ok the simple truth is most passenger tires start out with 13/32 of tred this would be the equivalent of 100%. most of the sellers especially the big sellers inflate the percent of the amount of tred left on there tires. They also like to play a game where they send you two good tires and two really worn tires and ask you to take a discount or send the tires back at YOUR cost. You should report them to ebay for "item not as described" as soon as you recieve the tires if they do not take the tires back and issue a COMPLETE refund. ( I just went through this with ""sgtdweber"" a tire seller that likes to play that game read his feedback.)

Tires do not wear less when they get more worn and when you get down to 3or4 32nds the tire is pretty much worn out.

If you want to figure the percent of tred left it is pretty simple take the tred that the tire started out with in most passenger tires it is 13/32 if you take 7/32 you would divide 7 by 13 then multiply that answer by 100 like this (7/13)x100=53.8% of the tred remaining.

12/32=92%  11/32=85% 10/32=77% 9/32=69% 8/32=62% 7/32=54% 6/32=46%