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Speedometer adjustment for different size tires.


Nightmaresmk

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:spin:I don't know if it's been adjusted in rom raider or not. My cobb unit i have been told no.

Trying to adjust my outback so it will read correctly with 255/40R17's. I currently run 255/50R17's but i now have a 6spd so i can decrease the size.

I read about a piggyback device that adjusts it but haven't fund one compatible with our cars.

I searched and found nothing on the subject.

Thanks for the help

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Hopefully you'll have better luck than I did, but my research told me it's not possible. Instead of having a single speed sensor in the transmission, our setups seem to utilize all four ABS sensors (one on each wheel). If it's even possible, you're looking at tricking/adjusting all four of these sensors at the very least from what I can tell.

 

Everyone I got into contact with just gave me a flat out no.

 

Run the tallest tire you can without having clearance issues and enjoy the expanded gearing of the 6mt, IMO. If you really want to stay small for acceleration / fitment of wider tires, just suck it up and deal with the speedometer difference. I've been marking down when I swap different tires on / off so I can calculate the actual odometer value down the road if I need to.

"Bullet-proof" your OEM TMIC! <<Buy your kit here>>

 

Not currently in stock :(

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  • 1 month later...

Ok going to throw out a curve ball. BarManBean lets try a different idea instead of adjusting the ecu for tire size. What calculates the speed.

Is it the ecu,bcu or the gauge cluster. Idea would be to swap to a Legacy gt or spec b version of that controls the speedometer calculation.

Or if you can have a dealership flash the legacy Gt firmware to our outback hardware. Would be a lot easier just to swap the hardware though.

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Try looking up the ABS sensor part numbers. Maybe if you replace all four of them you'll get a result. I think it's a combination of signals sent from all four ABS sensors and the ECU/other 'puters, but I don't know enough about how the actual speedometer works, honestly.

 

If the ABS sensor part numbers are different that could be the start of something.

"Bullet-proof" your OEM TMIC! <<Buy your kit here>>

 

Not currently in stock :(

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