Diesel Place banner

1 - 15 of 15 Posts

·
Registered
Joined
·
9,300 Posts
Discussion Starter #1
In the edge manual it says use figure X for H2 tire size. I then get a corrected speed on my attitude. When I divide my corrected speed by my displayed speed on truck I get 15% difference.

Some time back I saw a post that said H2 tires were 12% bigger.

What am I doing wrong?
 

·
Registered
Joined
·
6,995 Posts
What size did u put in?


The tires are 34.5" high.


Stock 245 are 30.6 and 680 rev/ mile


H2 315 are 34.5 and 601 rev/mile


so if u do the math it comes to 11.6% difference.
 

·
Registered
Joined
·
281 Posts
I run 285/75/16 on my truck. I came up with a 9% difference comparied to the stock size on the speedo. But then again I suck at math.


According to the Attitude at 60 mph my stock speedo says 55mph. My math was:


55mph x 1.09= 55.95mph


Thus being 9% difference.


Am I going about this the right way?


Jesse
 

·
Registered
Joined
·
124 Posts
Just curious here, but what number do you guys have in for th H2/315 combo?
 

·
Registered
Joined
·
958 Posts
The difference is almost exactly 12.8% with the H2's.
 

·
Registered
Joined
·
511 Posts
What Number Are You Entering In To The Attitude For The H2/315 Combo? ...is what he was saying.
 

·
Registered
Joined
·
9,300 Posts
Discussion Starter #9
I entered the number size on the side of the tire and compared to the book (edge) dont remember now what it was.
 

·
Registered
Joined
·
511 Posts
But 315/70-17 wasnt in the book
 

·
Registered
Joined
·
281 Posts
To get the exact measurement of your tires you have to draw a chalk line on your tire and on the ground at the same spot. Then drive forward until the chalk mark has rotated 360 deg. Then mark the ground again at that spot. Measure in between and use that number to program your edge. I think they use mm or cm. Thats how you know your speedo in the edge is perfect.


Jesse
 

·
Registered
Joined
·
9,300 Posts
Discussion Starter #12
K

sounds like a plan, thats what Ill do...
 

·
Diesel Master
Joined
·
1,858 Posts
The tire settings on the Attitude is the tire diameter in mm. To figure the diameter of a tire in mm, do the following. If you work through my example you'll see it is really a simple equation. BTW, i am not a math guy. Algebra was as far as I went.


((width x aspect ratio x 2) + (wheel diameter in inches x 25.4)) x pi = diamter in mm.


Applying this to my tire size (285/75s):


285 x .75 x 2 = 427.5


16 x 25.4 = 406.4


427.5 + 406.4 = 833.9


833.8 x 3.14159 = 2619.77


I then select the setting on the Attitude that most closely corresponds to that size.
 

·
Registered
Joined
·
511 Posts
Ok, I'll use 2741.97 for my H2 315s. Thanks
 

·
Diesel Master
Joined
·
1,858 Posts
Sounds right! For those intersted, 315/70R 17s are nominally 34.36" tall.
 
1 - 15 of 15 Posts
Top