sct didnt seem to change my speedo for tire size - Diesel Truck Forum - TheDieselGarage.com
Thread Details Posted by bigguy75inches, this thread has received 8 replies and been viewed 978 times.

 
LinkBack Thread Tools Display Modes
post #1 of 9 (permalink) Old 02-20-2007, 06:50 AM Thread Starter
 
Join Date: Jun 2006
Posts: 69
Points: 1,217
Thanks: 0
Thanked 0 Times in 0 Posts
sct didnt seem to change my speedo for tire size

hey guys, i upgraded from the stock tires to 35 inch tires. best i could tell the stockers were about 30 inches call, and my new tires are about 33.75 inches tall. its throwing my speedometer off im sure.. when i got my sct i was under the impression it would alter my speedo as well. but when i change the size on the sct it doesnt seem to make any affect on my speedo. if i got stock tuning or the sct tuning i still sit exactly at 2000 rpms at 70 mph. for a 33.76 diameter tire,, what revs per mile should i have it set at?


i may be wrong,, but this is how i figured i was suppose to do it.

33.75 times pi is 105.975. im gonna round to 106.

so 106 is my circumfrence in inches.

a mile is 5280 feet. that times 12 (inches in a foot) is 63360 inches in a mile.

63360 divided by 106 is about 597 or 8 revs per mile.

Does that sound right?????

If the sct doesnt actually affect my speedo,,, and my only option is to take it to the dealer,,,,, do i need to tell them a specific number??

thanks guys.
bigguy75inches is offline  
Sponsored Links
Advertisement
 
post #2 of 9 (permalink) Old 02-20-2007, 07:36 AM
Senior Member
 
Join Date: Dec 2008
Posts: 1,171
Points: 21,360
Thanks: 25
Thanked 56 Times in 24 Posts
You need to go to a dealer to get the speedo recalibrated. The SCT will reprogramm the trans so it shifts properly. Keith

U. S. Navy Seabee Veteran.

We build, we fight , we drink more beer.

When you are up to your butt in alligators it is heard to remember the reason you are here is to drain the darn swamp.
ktpauley is offline  
post #3 of 9 (permalink) Old 02-20-2007, 01:15 PM
MAFIA #8
 
hhrecovery's Avatar
 
Join Date: Dec 2008
Location: Pulaski, VA
Posts: 5,567
Points: 88,885
Thanks: 104
Thanked 223 Times in 209 Posts
Images: 1
Garage
yeah exactly what keith said.

Aaron - 2004 F350 "Offroad Edition"

2003 F250 "Pulling Truck"
hhrecovery is offline  
post #4 of 9 (permalink) Old 02-20-2007, 02:42 PM Thread Starter
Threadstarter
 
Join Date: Jun 2006
Posts: 69
Points: 1,217
Thanks: 0
Thanked 0 Times in 0 Posts
i still need to know what you guys think i should tell the dealer to flash it too?
bigguy75inches is offline  
post #5 of 9 (permalink) Old 02-20-2007, 03:02 PM
 
Join Date: May 2006
Posts: 269
Points: 1,446
Thanks: 0
Thanked 0 Times in 0 Posts
they should know what to change it to...
oh3_6oh is offline  
post #6 of 9 (permalink) Old 02-20-2007, 09:30 PM
Senior Member
 
Join Date: Dec 2008
Posts: 1,171
Points: 21,360
Thanks: 25
Thanked 56 Times in 24 Posts
I think the lowest revs per mile the dealer can recal for is 600 or close to that. 35's are the largest tires the dealer can do. Keith

U. S. Navy Seabee Veteran.

We build, we fight , we drink more beer.

When you are up to your butt in alligators it is heard to remember the reason you are here is to drain the darn swamp.
ktpauley is offline  
post #7 of 9 (permalink) Old 02-20-2007, 11:15 PM
MAFIA #8
 
hhrecovery's Avatar
 
Join Date: Dec 2008
Location: Pulaski, VA
Posts: 5,567
Points: 88,885
Thanks: 104
Thanked 223 Times in 209 Posts
Images: 1
Garage
yeah it isn't necessarily a flash just tell them you need to have it recalibrated for your larger tire size.

Aaron - 2004 F350 "Offroad Edition"

2003 F250 "Pulling Truck"
hhrecovery is offline  
post #8 of 9 (permalink) Old 02-21-2007, 12:10 PM
Pursuit Interceptor
 
HeavyAssault's Avatar
 
Join Date: Dec 2008
Location: Middle, VA
Posts: 735
Points: 60,388
Thanks: 15
Thanked 25 Times in 24 Posts
Images: 5
Ask the dealer to recal the ABS module for the new tires. I have asked why the SCT doesn't do this and was told the liability of screwing up the ABS was to great for the aftermarket guys to worry about.
I would look at the manfacturer's web site for the rotations per mile for your tire. They sometimes list the revolutions in the specs of the tire. If not go with the 601 value. If the dealer has a problem with that suggest to them using the OEM 20" wheel and tire combo value. It's hit and miss with the dealers so good luck on that end. If I remember right the Superlift Tru-Speed will adjust the ABS and speedo. I'd call Superlift first on that one.
HeavyAssault is offline  
post #9 of 9 (permalink) Old 02-21-2007, 02:29 PM
 
abrannan19's Avatar
 
Join Date: Dec 2008
Location: Jacksonville,FL
Posts: 504
Points: 54,412
Thanks: 142
Thanked 46 Times in 35 Posts
Like said above..SCT wont change your speedo ..and the dealer can only adjust up to 35's..

you need something like this..I don't have one..(don't care that much) but there are quite a few people on FTW that have them and say that they are the best speedo correction module that they have ever used..

http://www.fmdkinc.com/truck.htm

here are a few pics of my buddy Scott's truck..while he was installing the speed wizard

http://fordtruckworld.tenmagazines.c...4x4/698833.jpg
http://fordtruckworld.tenmagazines.c...4x4/698832.jpg
http://fordtruckworld.tenmagazines.c...4x4/698831.jpg
abrannan19 is offline  
Reply

Quick Reply
Message:
Options

Register Now



In order to be able to post messages on the Diesel Truck Forum - TheDieselGarage.com forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.

User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.

Password:


Confirm Password:
Email Address
Please enter a valid email address for yourself.

Email Address:
OR

Log-in










Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page
Display Modes
Linear Mode Linear Mode



Posting Rules  
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On

 
For the best viewing experience please update your browser to Google Chrome