Issues with AlfaOBD and changing tire size

[AEDELGOD]

Hey everyone,

Wondering if anyone else is running into this issue. I went to change the tire size on my buddy's 2015 Sport and followed everything to the T, looked up his tire size and all to get the correct mm size, etc. To keep a long story short, after many attempts at it I went an pulled my size off my 2014 and it was showing 1 over the max value (65535.000) so I did the same to his truck and low and behold his truck is no longer in limp mode but it is off by 4. So if he is going 60 it is reading 64. Wtf is going on with this and AlfaOBD? Is there a new bug or procedure that needs to be done that I am not aware of? Why on earth does AlfaOBD see my dynamic tire size as over the max value and how can I get my buddy's 2015 back to as close as possible? It was originally off by 1. It was originally set at the default 2570mm, and so was my truck, I took screenshots of the config before.

Any insights are appreciated, thanks!

 

[John Jensen]

I fine tuned mine by incrementally changing tire diameter size in mm. I have never had an accurate reading using tire sizes

 

[RamDiver]

I fine tuned mine by incrementally changing tire diameter size in mm. I have never had an accurate reading using tire sizes

When you say incrementally, did you just add a wild a$$ guessed amount or did you use an amount equivalent to the speedo error percentage and then retest?

.

 

[AEDELGOD]

What's throwing me off is mine and his truck used to say 2750mm but now says 65535mm (max value) and each normal value I put on my friend's truck puts it into limp mode but when I put the max value on his it became drivable again but off by 4 (slow) when it was originally only off by 1. I still have stock 275/60r20s on my truck so never ran the procedure on my truck and my truck is fine. His is out of whack now and I'm starting to wonder if something went wrong with the latest AlfaOBD update.

 

[John Jensen]

When you say incrementally, did you just add a wild a$$ guessed amount or did you use an amount equivalent to the speedo error percentage and then retest?

.

A little bit of both. Started with the % difference which got it close. (Actually got it right on with one truck) Finished with a bit of guessing which took 3 or 4 tries.

I was using my cell phone and a Garmin, looking at both speedo error and miles error. I found dealing with miles or odometer errors was the most accurate. I made sure the miles all agreed and let the speedo info fall in place. I wanted my MPG data to be accurate.

 

[RamDiver]

What's throwing me off is mine and his truck used to say 2750mm but now says 65535mm (max value) and each normal value I put on my friend's truck puts it into limp mode but when I put the max value on his it became drivable again but off by 4 (slow) when it was originally only off by 1. I still have stock 275/60r20s on my truck so never ran the procedure on my truck and my truck is fine. His is out of whack now and I'm starting to wonder if something went wrong with the latest AlfaOBD update.

So, if I understand the information correctly, your buddy's truck was set to 2750mm and off by 1 mph, is that correct?

Have you tested what happens if you set the wheel size back to 2750mm, test the speed accuracy, and then add 25-50mm at a time?

.

 

[AEDELGOD]

So, if I understand the information correctly, your buddy's truck was set to 2750mm and off by 1 mph, is that correct?

Have you tested what happens if you set the wheel size back to 2750mm, test the speed accuracy, and then add 25-50mm at a time?

.

Yes, it went into limp mode, locked up the electronic steering and had multiple codes for implausible data. AlfaOBD app says max possible value is the one it is set at now (same with my truck but never messed with mine like that - still have 20" sports on mine and original tire size, again, never did tire change procedure on my truck). I saved a screenshot of his tire size from April when we last adjusted it and it was 2750 which is supposed to be stock value for factory 20s which we both have/had. We originally adjusted it then to 2850 and it was off by 4 but otherwise fine so we were going to set it back closer to 2750 then all hell broke loose. AlfaOBD did have an update after the first time but wanted to see if anyone else had similar experiences and suggestions to this discrepancy. I did contact AlfaOBD about this too and sent them my screenshots.

 

[RamDiver]

A little bit of both. Started with the % difference which got it close. (Actually got it right on with one truck) Finished with a bit of guessing which took 3 or 4 tries.

I was using my cell phone and a Garmin, looking at both speedo error and miles error. I found dealing with miles or odometer errors was the most accurate. I made sure the miles all agreed and let the speedo info fall in place. I wanted my MPG data to be accurate.

Thanks for that info, John.

I plan to buy AlphaOBD soon, I already have a bypass cable and the Bluetooth dongle.
Starting with the percentage error sounded logical but even better after your confirmation.

This activity is on my list after I install a starter kill switch assembly from JW2 Innovations.

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[RamDiver]

Yes, it went into limp mode, locked up the electronic steering and had multiple codes for implausible data. AlfaOBD app says max possible value is the one it is set at now (same with my truck but never messed with mine like that - still have 20" sports on mine and original tire size, again, never did tire change procedure on my truck). I saved a screenshot of his tire size from April when we last adjusted it and it was 2750 which is supposed to be stock value for factory 20s which we both have/had. We originally adjusted it then to 2850 and it was off by 4 but otherwise fine so we were going to set it back closer to 2750 then all hell broke loose. AlfaOBD did have an update after the first time but wanted to see if anyone else had similar experiences and suggestions to this discrepancy. I did contact AlfaOBD about this too and sent them my screenshots.

So, you had set it to 2850mm and all was well except the speedo was off by 4mph, correct?
Was it reading 4mph high or low?

FYI, 100mm=4" which is a considerable difference from the OEM setting.

So what changes were made next or exactly what is the definition of "all hell broke loose"?

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[AEDELGOD]

So, you had set it to 2850mm and all was well except the speedo was off by 4mph, correct?
Was it reading 4mph high or low?

FYI, 100mm=4" which is a considerable difference from the OEM setting.

So what changes were made next or exactly what is the definition of "all hell broke loose"?

.

So I've only done the tire change procedure to it. Went into BCM and ran that procedure, disconnected, cycled key off waited a minute, turned it back to run. Then connected into ABS and did ECU initialization, cleared CELs, disconnected, cycled off and back to run, then did clearing rolls information, cleared CELs in ABS, BCM, then PCM. All standard procedure we've done before. When turned on power steering was locked up and multiple CELs for implausible data. Repeated for multiple types of common values including the stock option in the drop-down which is the Goodyear Wrangler SR-A 275/60r20 which set the value of 2750mm. It didn't like it, same results. Went to my truck and pulled the value on mine and my truck said 65535mm and used that value into his so it could be drivable again but off by 4 again. 65535mm (max value according to AlfaOBD is 65534mm) sounds outrageous and never showed that before on either truck.

 

[CanRebel]

Not sure if this will help or not, as I have 5th Gen.

I changed the rim and tires on my Rebel. Every tire website gave me same number. When I would enter it, I would get crazy codes, half the truck was disabled.

So I put back original number. And then slowly increased the number manually, until it would throw codes, then backed it up one. It's technically off by 1-2 on speed, but close enough that I don't care.

 

[RamDiver]

So I've only done the tire change procedure to it. Went into BCM and ran that procedure, disconnected, cycled key off waited a minute, turned it back to run. Then connected into ABS and did ECU initialization, cleared CELs, disconnected, cycled off and back to run, then did clearing rolls information, cleared CELs in ABS, BCM, then PCM. All standard procedure we've done before. When turned on power steering was locked up and multiple CELs for implausible data. Repeated for multiple types of common values including the stock option in the drop-down which is the Goodyear Wrangler SR-A 275/60r20 which set the value of 2750mm. It didn't like it, same results. Went to my truck and pulled the value on mine and my truck said 65535mm and used that value into his so it could be drivable again but off by 4 again. 65535mm (max value according to AlfaOBD is 65534mm) sounds outrageous and never showed that before on either truck.

OK, thanks for those details.

It appears as though you've followed the procedure correctly, as far as I can see. Hopefully, someone with more experience using AlphaOBD will see any possible errors in the procedure or have recommendations on what to try next.

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[Dean2]

I would contact Alexey the developer and get some help. Something isn't right but I can't tell what is off.

 

[John Jensen]

They say on the newer trucks you don't need to do an ABS Initialization. I have a hunch that in some cases where there's a problem with the tire size change not taking effect, maybe the ABS does need Initializing. Here is an older link that does a good job of describing the process. Maybe it will help
Tire size change and ABS Initialization

 

[AEDELGOD]

They say on the newer trucks you don't need to do an ABS Initialization. I have a hunch that in some cases where there's a problem with the tire size change not taking effect, maybe the ABS does need Initializing. Here is an older link that does a good job of describing the process. Maybe it will help
Tire size change and ABS Initialization

ABS initialization is greyed out for us. He has a 2015 Sport and I have a 2014 Lone Star. Doesn't let us select start on that menu. It's definitely taking our changes though.

The issue that is racking my brain is I've never done this procedure before on my own truck and I have stock 20" wheels and it I checked what mine are set at and AlfaOBD is saying it is 65535mm, which that can't be right.

As a hail mary we set my friends truck to that and now it's drivable but off by 4 and he texted me this morning saying his steering isn't quite right still.

I've emailed Alexey from AlfaOBD and we've emailed back and forth a little bit not much from him yet, just answering all his questions.

 

[RamDiver]

ABS initialization is greyed out for us. He has a 2015 Sport and I have a 2014 Lone Star. Doesn't let us select start on that menu. It's definitely taking our changes though.

The issue that is racking my brain is I've never done this procedure before on my own truck and I have stock 20" wheels and it I checked what mine are set at and AlfaOBD is saying it is 65535mm, which that can't be right.

As a hail mary we set my friends truck to that and now it's drivable but off by 4 and he texted me this morning saying his steering isn't quite right still.

I've emailed Alexey from AlfaOBD and we've emailed back and forth a little bit not much from him yet, just answering all his questions.

Please keep us posted on any new developments.

.

 

[SitKneelBend]

ABS initialization is greyed out for us. He has a 2015 Sport and I have a 2014 Lone Star. Doesn't let us select start on that menu. It's definitely taking our changes though.

The issue that is racking my brain is I've never done this procedure before on my own truck and I have stock 20" wheels and it I checked what mine are set at and AlfaOBD is saying it is 65535mm, which that can't be right.

As a hail mary we set my friends truck to that and now it's drivable but off by 4 and he texted me this morning saying his steering isn't quite right still.

I've emailed Alexey from AlfaOBD and we've emailed back and forth a little bit not much from him yet, just answering all his questions.

Did you happen to upgrade your phone recently? If so, you old phone (if available) might have an older version of the app to try? Just don't let it update when you fire it up.

 

[AEDELGOD]

Please keep us posted on any new developments.

.

Preliminary, it appears to be a read/display bug with the app not giving the correct/current value. I've reported my findings to Alexey just now. I was able to correct my friends truck but I had to put my programmer hat on and really critically think through how the software code is likely working, so I was working blind but got it all in good working order and being off about 1mph on the speedometer.

Did you happen to upgrade your phone recently? If so, you old phone (if available) might have an older version of the app to try? Just don't let it update when you fire it up.

I wish, I was about to start looking for older versions of the APK but Alexey hasn't been very responsive during all this.

 

[SitKneelBend]

Preliminary, it appears to be a read/display bug with the app not giving the correct/current value. I've reported my findings to Alexey just now. I was able to correct my friends truck but I had to put my programmer hat on and really critically think through how the software code is likely working, so I was working blind but got it all in good working order and being off about 1mph on the speedometer.

I wish, I was about to start looking for older versions of the APK but Alexey hasn't been very responsive during all this.

I looked too but it doesn't appear those are published anywhere. From my understanding, Alexei can get busy but once he does respond he's very responsive. If I find an installable APK I'll let you know.

 

[Big3MG]

You would take the tire off and measure the diameter with a tape measure and convert inches to mm. But always check with Waze as this GPS app shows actual speed. Then go back and tweak it. Google can tell you how many inches or mm to increase or decrease based on mph displayed vs actual. It never works using some factory tire size / diam.