ZR17 Just means that it is z speed rated for a 17 in. rim. The 275 is the width and the 40 is the sidewall hight.

in that tire example, 275 (the first 3 digit number) is the measurement in mm across the tire, from where it meets the rim on one side, all the way across to where it meets the rim on the other side. the second number, 40 in this case, is the percentage of the first number that makes up the sidewall height. so 40 percent of 275 is 110, so your sidewalls are 110mm tall. The smaller the second number, the smaller the sidewall, low profile tires or "low-pros" are considered 50 in the second numbers place or lower. the last section (in this case ZR17) the "Z" is the tire speed rating. if i'm not mistaken the Z is 169mph speed rating, but i'm not 100% positive. the R just means rim, and the 17 is the diameter the tire is meant to fit. so just for an example, a 275/40/17 would be a shorter tire than a 275/50/17, but both tires have the same contact patch, but the seconds is just a little bit taller. and by the way it sounds like the tires you are looking at are nitto drag radials, which are bad ass tires, but look to replacing them in about a year. that is, if you drive like me....

haha, those are the exact same tires im getting! thanks so much for helping me out! :banana: :dancing6: O0