245-265 thoes first numberes are the width of the tire, the second is the side wall hight, and is a persentage of the width, so the second number is going to relate to your overall hight, but changes with wheel size,

 

Means they are of age?

 

trucker, I was out of my mind when I typed that. I was on ambien after a 20 hour mission. So ANYway...regardless of the measurement...does a smaller circumference tire hail improvements yay or nay?

 

lghtngblt02 Since we are running the same stock wheel from Chrysler any idea what the back spacing is on our stock wheels? Cya Slick

 

it may be lighter?

therefore like .1 more mpgs.

 

No, I'm pretty sure the smaller tire roating less times over a distance of one mile over say an offroad tire makes it easier on the vehicle. Same revs and less 'distance' to cover for one complete rotation equates to better mileage and even torque. I guess this forum needs more scientists? I basically answered my own question but was trying to see if anyone else had heard of this.

 

Well circumference is just a function of the diameter. A tire with a larger diameter will cover more ground in one rotation, a tire with a smaller diameter will cover less ground. Going to a taller tire is like going to numerically lower gearing and vice versa for a shorter tire. Whether or not it equates to better mileage has to do with city vs highway and can be tricky, it is also complicated by taller tires often weighing more. But you are a little off the smaller tire will have to rotate more times over a distance of one mile.

The easiest way to look at it is like this: the circumference of your tire is how far you will move with exactly one revolution of the tire. To prove what I said above take your mile and divide it by the circumference of the shorter tire, then the mile by the circumference of the taller tire and compare the two.

 

Yah that's what I meant, smaller goes more times, which creates the disadvantage of tire wear. I don't see why you mentioned diameter... obviously a larger diameter covers more ground because that makes it a longer circumference...so why not just say a tire with bigger circumferece? More syllables? Haha.
I see what you mean with it having benefits in certain areas ie:city vs. highway because it is changing your gearing slightly with the smaller tire. So, basically it goes back to do what looks better!
good stuff.

 

Nah, just wanted to make it easier for everyone, a lot of people think of tires in terms of height.