When i change my tire size im not sure what is the correct size? i have 305/35/24 wheels so what would that be in MM's to put into the edge

 

I thought I remember the numbers being in the thousands but there are 25.4mm in an inch.

A 305/35/24's overall diameter is 32.41 inches. So that equals 823.41mm.

 

different brands of the same size tire can be off from each other in heigth

 

So do you know if I was right? I kind of want to know now.

A metric tire size is going to be damn close to the true size.

 

I think you need to redo your math there thumper

I get 2584.89mm

(32.41)(3.14)(25.4) = 2584.89

I'm not a certified engineer yet but I'm pretty sure thats it.
Remember your not imputing the diameter of the tire, but the circumference.
I also read on here that its more accurate if you measure out your tires circumference by marking the ground and rolling it one revolution, seems to be more accurate.

 

wakborder your right, but yeah 305/35/24 is close to the size but not exatly, deffinatly measuer the actual tire in inches then multiply by 25.4 (ubless you have a metric tape measure)

 

305/35-24

*2585mm or 622 Rev/Mile at 0% squish factor
*2565mm or 627 Rev/Mile at 3% squish factor <-- More accurate on low-profile tires
*2551mm or 631 Rev/Mile at 5% squish factor <-- More accurate on high-profile tires

I'd go with the 2565mm.

 

I thought it was wrong, like I said, but where does the 3.14 come from?

 

Circumference (which is used by the programer) is equal to diameter x PI. or more priecisely:

C = PI * D
2585mm = 3.1415926 * 823.1mm

PI = 3.1415926535897932384626433832795 (Ok, overkill)

Also, to get Rev/Mile...
1609344 (mm/Mile) / Circumference (mm/Rev) = Rev/Mile

The same also works with inches to give Rev/Mile except you use 63360 (in/Mile) instead of 1609344 (mm/Mile).

 

LMAO. Wow, talk about a major brain fart.

 

Guys, I wanna thank all of you for the input cause i was using the measurements from an online tire calculator and their number was 2583 so thats what i put in the edge. is that okay or should i put in the 2565?

 

I have the best luck with 3% squish on profiles of 50 or lower. Above that I use 5% squish values.

The difference you are talking about is less than 1% of the circumference which is less than 1 MPH at 100 MPH. I wouldn't worry about it unless you are REALLY picky.

As a side note... if you go to the tire manufacturer's websites, they often have Rev/Mile values for the tires. I know Goodyear does and it is very easy to calculate to get the correct mm. 1609344 / revs = size in mm.