Welcome to the North American Subaru Impreza Owners Club Thursday September 20, 2018
Home Forums WikiNASIOC Products Store Modifications Upgrade Garage
Click here to visit TireRack
Tire & Wheel Forum sponsored by The Tire Rack

Losing traction? Need new tires?
Click here to visit the NASIOC Upgrade Garage...
Go Back   NASIOC > NASIOC Technical > Tire & Wheel

Welcome to NASIOC - The world's largest online community for Subaru enthusiasts!
Welcome to the NASIOC.com Subaru forum.

You are currently viewing our forum as a guest, which gives you limited access to view most discussions and access our other features. By joining our community, free of charge, you will have access to post topics, communicate privately with other members (PM), respond to polls, upload content and access many other special features. Registration is free, fast and simple, so please join our community today!

If you have any problems with the registration process or your account login, please contact us.
* Registered users of the site do not see these ads. 
Reply
 
Thread Tools Display Modes
Old 06-22-2018, 10:54 AM   #1
dilAY571
Scooby Newbie
 
Member#: 300837
Join Date: Nov 2011
Location: ST. Louis MO
Vehicle:
2004 WRX
WRB

Default Vehicle speed calibration?

I bought an SG XT recently. It came with aftermarket wheels and they're smaller than stock so my speedo is off. I don't really want to get new tires just to fix this because they are basically brand new. I've been looking at options and found the "Yellow Box Speedo Recailbrator" (https://yellr.com/yb_home.htm). Concept seems solid and I've read decent reviews from other people but I wan't able to find anything specific to a Subaru.

I like the idea of installing one of these because I could then run whatever size tire I wanted and still have accurate ODO/Speedo readings. I know I can "do a mental calculation" but that doesn't help when I let someone else drive my car and have to explain "the speedometer isn't accurate".

My question is this: Does anyone know if the vehicle speed is a direct input from the sensor in the trans or does it get calculated with inputs from the ABS sensors too? I'm worried I could install a YB and then hit limp mode or something because the ECU has some safeguards I don't know about.

Thanks
* Registered users of the site do not see these ads.
dilAY571 is offline   Reply With Quote
Sponsored Links
* Registered users of the site do not see these ads.
Old 06-22-2018, 12:18 PM   #2
Charlie-III
NASIOC Supporter
 
Member#: 30669
Join Date: Dec 2002
Chapter/Region: Tri-State
Location: USA, North NJ, 07456
Vehicle:
1998 Legacy 2.5GT
Silver Sleeper BK, 5MT

Default

Stop.....
Just because the rims are a different OD, does not mean the speedo/odd are incorrect.
You can play with tire width and sidewall aspect ratio and maintain a stock TIRE OD which is what is important.
Some tire places have online tire calculators to allow changing rim size and matching tires to maintain the OD.
If you have a GPS, go drive 55MPH and some other speeds and see the GPS speed vs. speedometer. Most are calibrated for 55.

Beyond that, I can't tell you the answer.

What year XT?
Charlie-III is offline   Reply With Quote
Old 06-22-2018, 02:03 PM   #3
dilAY571
Scooby Newbie
 
Member#: 300837
Join Date: Nov 2011
Location: ST. Louis MO
Vehicle:
2004 WRX
WRB

Default

Tire has a different OD. I know you can play with it. I have 18's on my WRX that I did that with. I didn't buy these tires though and I don't want to replace them because they have maybe 5k miles on them.

'05 that I'm very happy with. This is just something that I'm mildly annoyed with and I'm curious about. If I end up getting one of the Yellow Boxes I will do a write up if the install and post on here so others can learn from my trial and error.
dilAY571 is offline   Reply With Quote
Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not 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
Forum Jump

All times are GMT -4. The time now is 12:56 AM.


Powered by vBulletin® Version 3.7.0
Copyright ©2000 - 2018, Jelsoft Enterprises Ltd.
Powered by Searchlight © 2018 Axivo Inc.
Copyright ©1999 - 2017, North American Subaru Impreza Owners Club, Inc.