differential/speedometer/tire size math
#1
Registered User
Thread Starter
Join Date: Oct 2008
Location: Edmonton
Posts: 510
Likes: 0
Received 0 Likes
on
0 Posts
differential/speedometer/tire size math
Okay… I have 35 inch tires on my truck and just swapped my 3.73 gear ratio for 4.10. What tire size would I dial into the ECU so my Speedometer is correct?
#2
Registered User
Join Date: Oct 2006
Location: Kennewick, WA
Posts: 503
Likes: 0
Received 0 Likes
on
0 Posts
Check out the link for a chart and formulas for tire sizes and gearing.
http://www.4lo.com/calc/geartable.php
http://www.4lo.com/calc/geartable.php
#3
Registered User
Since the 3rd Gen trucks use an sensor ring on the rear differential ring for ABS and speedometer sensor, changing the ring and pinion ratio does not affect the speedometer and odometer.
Start with 35" in EFI Live and then check it with a GPS or a GPS app in a Smart Phone. Or find a place on the highway with the "mile marker" signs.
Start with 35" in EFI Live and then check it with a GPS or a GPS app in a Smart Phone. Or find a place on the highway with the "mile marker" signs.
#4
Registered User
Join Date: Feb 2006
Location: Woodstock, Georgia
Posts: 120
Likes: 0
Received 0 Likes
on
0 Posts
Excellent gear/tranny/tire speed calculator
Just a FYI and good reference to have ------>
Here is an excellent gear/tranny/tire speed calculator that was developed by Klenger.
The link is here:
http://klenger.net/dodge-ram/
Scroll down under the Dodge Ram section and find the "Gear Speed Tables" Excel link and download it for future reference. You can pick any available transmission, rear gear, tire size and it will calculate your speed. You can click on either the PDF link for online calcs or the Excel link to download if my memory serves me well.
(Thanks to Klenger for going to the trouble to develop it.)
Here is an excellent gear/tranny/tire speed calculator that was developed by Klenger.
The link is here:
http://klenger.net/dodge-ram/
Scroll down under the Dodge Ram section and find the "Gear Speed Tables" Excel link and download it for future reference. You can pick any available transmission, rear gear, tire size and it will calculate your speed. You can click on either the PDF link for online calcs or the Excel link to download if my memory serves me well.
(Thanks to Klenger for going to the trouble to develop it.)
#5
Registered User
Thread Starter
Join Date: Oct 2008
Location: Edmonton
Posts: 510
Likes: 0
Received 0 Likes
on
0 Posts
Cool, thanks!
I figured out that the truck Speedometer is reading 6 km/hr too fast. Maybe it has never been corrected from the last tune I did and this is the difference between 33 inch tires and 35 inch tires.
I figured out that the truck Speedometer is reading 6 km/hr too fast. Maybe it has never been corrected from the last tune I did and this is the difference between 33 inch tires and 35 inch tires.
Thread
Thread Starter
Forum
Replies
Last Post
dr450r
4th Gen High Performance and Accessories 2010 and Up
4
10-17-2012 11:34 AM
bigdogtruck
2nd Gen. Dodge Ram - No Drivetrain
18
11-21-2007 08:09 PM
4RnrRick
1st Gen. Ram - All Topics
4
02-27-2007 11:25 AM