Best gears
Jun 2, 2011 | 08:55 AM
Joined: Jun 2005
Posts: 4,243
Likes: 16
From: AZ
Quote:
Originally Posted by
JOHN2001
If I go 40s I'll go 13.5 wide if I go 38s I'm gonna go 15.5 nitto mud grapplers either way thanks for your help fellas
Is the aspect ratio 80 (ratio of the sidewall height to tread width) as Jeff described?
Never mind...I calculated the aspect ratios and here is what I show for RPM.
Given 4R100 tranny, 4.30 gear, 40" tires (13.5" wide), 70 MPH = 1782 RPM:
Given 4R100 tranny, 4.30 gear, 38" tires (15.5" wide), 70 MPH = 1905 RPM:
And here is the 4.56 gearing info (just in case you wanted to compare): Given 4R100 tranny, 4.56 gear, 38" tires (15.5" wide), 70 MPH = 2020 RPM:
Given 4R100 tranny, 4.56 gear, 40" tires (13.5" wide), 70 MPH = 1890 RPM:
Jun 2, 2011 | 11:00 AM
Thread Starter
|
Logistics Pro
Joined: Dec 2010
Posts: 4,738
Likes: 15
From: Temperance, MI
Thanks Neal that's a big help. What are you guys spinning at 70 with stock gears so I know which one is the better ratio?
Jun 2, 2011 | 11:10 AM
Joined: Jun 2005
Posts: 4,243
Likes: 16
From: AZ
I believe my dually is geared at 4.10, so the RPM at 70 MPH with 235/85R16's would be 2159 RPM. With 3.73's and the same tires it would be 1964 RPM.
Jun 2, 2011 | 11:55 AM
Thread Starter
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Logistics Pro
Joined: Dec 2010
Posts: 4,738
Likes: 15
From: Temperance, MI
4:30 gears are looking good to me because I do like to get some kind of hwy fuel economy. 4:30 and I'm leaning more toward the 38s now
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