Alternate wheel size and speedo question - can it be corrected?

[kungfujedis]

While I'm waiting to take delivery of my Supra in mid-January, I am trying to figure out my wheel/tire situation. I'm going to run separate street/track sets. What I haven't decided is which set will be which. One factor in my choice of street tire/wheel will be if the speedo can be corrected if it's not stock size. I've done quite a bit of research and searching, but I haven't been able to determine if the speedometer can be adjusted for a different tire diameter. I see from reading the manual that you can enter tire information into the car, including the size. If you tell it you are using something like 275/35-18, will it do the math to adjust the speedometer? If not, can that be fixed with something like bimmer code? Thanks!

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[razorlab]

While I'm waiting to take delivery of my Supra in mid-January, I am trying to figure out my wheel/tire situation. I'm going to run separate street/track sets. What I haven't decided is which set will be which. One factor in my choice of street tire/wheel will be if the speedo can be corrected if it's not stock size. I've done quite a bit of research and searching, but I haven't been able to determine if the speedometer can be adjusted for a different tire diameter. I see from reading the manual that you can enter tire information into the car, including the size. If you tell it you are using something like 275/35-18, will it do the math to adjust the speedometer? If not, can that be fixed with something like bimmer code? Thanks!

You can take out the +3mph buffer with Bimmercode and that helps. The tire info screen won't correct anything.

I also believe you can calibrate it in Protool for a different diameter but I haven't dove into that too much.

 

[BMWAF]

You can take out the +3mph buffer with Bimmercode and that helps. The tire info screen won't correct anything.

I'm not sure this works very well. I experimented with some codes and it would appear the exact setting we need isn't available for our cars. The one we can change actually messes with the cruise control so it isn't in sync with the speedo.. which annoyed me more than the 3mph discrepancy.

Very happy to be wrong if anyone knows the exact coding needed to fix this.

 

[Sharocks]

It's gonna be off by a few MPH.

Unless you have severe OCD, I'd worry about other things.

 

[digicidal]

We have a few places around here where the police have been gracious enough to put "calibration signs" up... all I know is my speedometer is accurate to "SLOW DOWN" - whatever that means.

 

[razorlab]

I'm not sure this works very well. I experimented with some codes and it would appear the exact setting we need isn't available for our cars. The one we can change actually messes with the cruise control so it isn't in sync with the speedo.. which annoyed me more than the 3mph discrepancy.

Very happy to be wrong if anyone knows the exact coding needed to fix this.

I have it working on my car, although I never use cruise control.

 

[BMWAF]

I have it working on my car, although I never use cruise control.

Do you remember the coding you applied?

Here is the code I tried that worked but didn't apply to the cruise control putting it out of sync:

Instrument Cluster > Expert > 3000 Anzeige_Konfiguration > BC_V_KORREKTUR - set to ohne_korrektur.

Maybe there's another code we could use to correct the cruise control read out?

 

[razorlab]

Do you remember the coding you applied?

Here is the code I tried that worked but didn't apply to the cruise control putting it out of sync:

Instrument Cluster > Expert > 3000 Anzeige_Konfiguration > BC_V_KORREKTUR - set to ohne_korrektur.

Maybe there's another code we could use to correct the cruise control read out?

I don't. I actually think I used Protool to do it.

 

[Habu]

We have a few places around here where the police have been gracious enough to put "calibration signs" up... all I know is my speedometer is accurate to "SLOW DOWN" - whatever that means.

I have these signs in my area & I recently realized not only do they say "SLOW DOWN" but also, "TOO FAST" at a certain speed threshold. Ive discovered this the other day driving the Supra lol.

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