Trying to program Forscan for switch to 35s- Help Please!

[Fishfood]

I have a '24 Badlands non SAS and I have SAS wheels and now have now swapped in 35" K02s for the stock 33" K02s. When I went into Forscan and changed the tire circumference, I got a bunch of errors and was unable to clear them out. I tried a couple different numbers but ultimately had to go back to the 2525 stock number to get things back to normal. Anyone know the process and the proper circumference to use? I tried 2625, 2742 and a couple others I saw online.

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[RagnarKon]

After you program you have to relearn vehicle data so it gets updated in the remaining modules. Otherwise is gonna throw errors due to the mismatch.

2653 is the factory value for 35s, other sizes should work, but if you have issues still you can try 2653.

 

[Brian_B]

Did you do the PCM Init procedure afterwards? The DTCs won't clear unless you do.

https://www.bronco6g.com/forum/thre...eedometer-with-forscan-for-2021-bronco.23064/

 

[Fishfood]

Ok! Will give the relearn a try tomorrow. The video looks pretty clear.

 

[GA2Dr]

I have Mickey Thompson Baja Boss 35's. 2600 was spot on for me. Have to do the re-learn as others have said.

 

[Fishfood]

2653 is the factory value for 35s, other sizes should work, but if you have issues still you can try 2653.

Is this the factory number for 315s or true 35?

 

[Umichigan1]

After you program you have to relearn vehicle data so it gets updated in the remaining modules. Otherwise is gonna throw errors due to the mismatch.

2653 is the factory value for 35s, other sizes should work, but if you have issues still you can try 2653.

I had to tweak my numbers when I moved to 35s. I measured the circumference manually with the tires under load. Then I put the number in Forscan. When I checked my speed (using various methods) I found that it was still off. I tweaked the number bit by bit until I reached a number that seemed adequately calibrated.

 

[Brian_B]

My advice for “the number”

Be willing to do some trial and error - Forscan math isn’t precise.

 

[RagnarKon]

Is this the factory number for 315s or true 35?

Neither.

Factory 315/70R17. And it is a rather conservative number—better to overestimate speed than underestimate speed obviously.

Very few "true" 35s on the market though. Even 35X12.50R17 tires are usually around 34.5" - 34.7". So good chance the factory value will be close.

 

[Superchips_Mktg]

For anyone who would rather not do the math, our new Flashcal+ has a GPS based Tire Size Wizard that will calibrate your speedo for you

https://www.holley.com/products/tun...ers/bronco_flashcal_plus_wireless_calibrator/

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