Im getting 17's for my focus and i see that there are different types to choose from!
Some say 205/40/17 and then some say 215/45/17! I get what the 17 stands for but not quite sure what the first two numbers are saying!

sidewall and width of the tire

205 is the width of the tire, and the 40 is the ratio of sidewall compared to the width. The 205/40's will give you more grip than the 215's because the 205's are a lower profile rubber.

first number is the width..the second is the aspect ratio which is ratio of sidewall hieght to width and the last number is diamter of wheel in inches

wtf i hate that..how u are sayin sumtin then u send it and then boom all these other ppl said the same thing but u dont kno till u send urs!

First number is the width of the tire (in MM). The second number is the series. The series is how tall the sidewall is. Like say the series is 40, the sidewall height is 40% of the width of the tire. Also http://www.tirerack.com/tires/tiretech/general/size.htm has a good explanation.

Originally posted by FoRdFoCuZdRiVeR
wtf i hate that..how u are sayin sumtin then u send it and then boom all these other ppl said the same thing but u dont kno till u send urs!
[hah] [hah] I just started laughing when I saw that.

Ok Thanks a bunch!

I just found this site. It'll tell you the overall tire height without all of the "painfull" calculations.

http://www.juric.org/mopar/tools/tirecalc.php [thumb] [thumb]