Tire size change alfaOBD

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1500ram12

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I would say your best bet at this point is to clear any codes in the ABS/BCM/ECM Modules and then disconnect the battery then turn the headlights on wait a couple minutes and reconnect the battery so you can start over fresh.

Are you using the current update or an older one?

These would be my next steps. Then give your truck a little rest then try again


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WilliamS

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These would be my next steps. Then give your truck a little rest then try again


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No matter what I pick tire wise I can not move forward without a value in the mm section. I thinks it’s a flaw in the setup. If I pick a preselected tire I can not start without a value in the mm

I was able to get it back to drive able, again it picked some tire on a 19.5 wheel and I put in the mm size and it’s dead on with gps. Cleaned out the 200 check engine lights and moved on. I’ve coded cars for years, and this thing it just a fussy monster.
 
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1500ram12

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What size tire do you have


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WilliamS

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What size tire do you have


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Stock RS/A now. Next week she gets lifted and putting back on my 295/65-20.

Everything else up to this hasn’t been an issue. Setup fogs with high beams, added menus, DRL all worked. Tire size seems to be the hiccup at least on this version on my z3 phone. I have the mx+ adapter, and to be honest my $3 WiFi obd adapter has worked better that the mx so far in testing
 

1500ram12

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So your 295's are a 35" tire, a good chance that they will actually measure out at ~34.5". So 2752mm will be what you want to use. I'd skip trying to use any pre determined tire sizes. It might be a glitch that will have to be addressed in an update.

Have you updated the software for your mx+? If not in the instructions will tell you how to do so. Then I'd unistall and reinstall alphaobd. I've had zero issues using alphaobd on a kindle fire 7 and a galaxy note 5. So your phone shouldn't be an issue.


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WilliamS

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So your 295's are a 35" tire, a good chance that they will actually measure out at ~34.5". So 2752mm will be what you want to use. I'd skip trying to use any pre determined tire sizes. It might be a glitch that will have to be addressed in an update.

Have you updated the software for your mx+? If not in the instructions will tell you how to do so. Then I'd unistall and reinstall alphaobd. I've had zero issues using alphaobd on a kindle fire 7 and a galaxy note 5. So your phone shouldn't be an issue.


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They measure up to 35.1 nitto ridge grappler but close enough. I’m going to let it think I have a semi tires and just change the mm and hope for the best.

I think it is a glitch with the predetermined tire size but now I know how to circumvent it.

Also thank you for the quick response to try and help

it’s a programmer vs end user issue. I’m positive the thinking of how it was written is great in theory but is users are a different animal.
 

1500ram12

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They measure up to 35.1 nitto ridge grappler but close enough. I’m going to let it think I have a semi tires and just change the mm and hope for the best.

I think it is a glitch with the predetermined tire size but now I know how to circumvent it.

It must be a glitch with the predetermined sizes.

The size the manufacturer list or the size a tire calculator says isn't the true height of the tire. I measured my 35's and they are right about 34.5" and my 275/65 r20 which says it's a 34.1" measures out roughly to a 33.5".


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Mrmagoolin

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I changed tire size using only the predetermined size, but it has been a couple of alfa updates ago.
 

WilliamS

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I changed tire size using only the predetermined size, but it has been a couple of alfa updates ago.

As of right now I can not pick a predetermined tire and hit start, if the mm box is blank you can not move forward without a value. At least on the few I’ve tried that match my trucks current tires. Somehow the random works so I’ll use it.
 

Opie011

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I have 285/75/18 Ridgegrapplers and Nitto says they're 35.1" tall. I set the circumference to 2690mm(33.7" tall) and my speedo is accurate. Forgot what they measure when mounted but pretty sure they are taller than 33.7"...but hey the speedo is accurate!
 

Mrmagoolin

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As of right now I can not pick a predetermined tire and hit start, if the mm box is blank you can not move forward without a value. At least on the few I’ve tried that match my trucks current tires. Somehow the random works so I’ll use it.

I was only saying this as I think you are correct in there being a bug in the system. Have you contacted the developer?
 

WilliamS

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I was only saying this as I think you are correct in there being a bug in the system. Have you contacted the developer?

Going to when I have time to do it and fix it. Having a truck nearly disabled and have to fuss my way through it to make it drive able is wildly undesirable right this moment
 

Bikesanddiesels

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Hey guys,

2014 3500 Limited Cummins

So I changed my tire size, got the Christmas tree dash and freaked out. Followed the ABS initialazation but didnt find the post outlining the step by step cycling the key and clearing codes. Had a weird CEL that said low voltage mode.

I did it again following the steps exactly. Twice actually. (I need to service the rear parking sense) and every time I remote start the truck the dash is super dim, I start it and at 25mph the ride sense off and need to service ping back and fourth for about 5-7m of driving then goes away until I start the engine again.

I’ve put it back to the original tire size and it’s still doing it. I changed reverse light to led yes. And put that back as well. Still doing the weird thing.

Any ideas? I’d love to know how to correctly do the battery reset if that would do the trick. I also read that doesn’t work for 2014’s? Scares the crap out of me disconnecting batteries when it’s not just the one.

Sorry for the noob questions. But I am new to diesel and not afraid to admit my poor knowledge.

Thank you!
 

fyreman

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It must be a glitch with the predetermined sizes.

The size the manufacturer list or the size a tire calculator says isn't the true height of the tire. I measured my 35's and they are right about 34.5" and my 275/65 r20 which says it's a 34.1" measures out roughly to a 33.5".


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What formula are you using to calculate the "mm" I'm running 275/65 20 what would be a good starting entry for me. I had a heck of a time un f-ing my cluster earlier today. I figured I'd do it all over again tomorrow. Thanks

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Ghost_RAM

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1500ram12

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What formula are you using to calculate the "mm" I'm running 275/65 20 what would be a good starting entry for me. I had a heck of a time un f-ing my cluster earlier today. I figured I'd do it all over again tomorrow. Thanks

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https://tiresize.com/calculator/


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fyreman

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Well I just used the link you provided and hit the small mm button. BOOM. That is more realistic than the 5700 numbers that I was getting before. THANK YOU

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eraser888

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Hi guys,

I did try to change my tire size yesterday but it didn't seems to worked. Based of documentation, after applying the change in BCM-->Program Tire Size, after cycle key, I am suppose to get flashing lights in my dash but I didn't have anything light up. I did try to reset the ABS as described in doc but finally, it doesn't seems to have any effect on my speedometer.

One thing strange, in AlfaOBD, when I go in "battery" section to read IDS, in "Vehicule Config 4 --> Dynamic Tire Circumference", it always stay at the same number "2640,00 mm". But when I go in BCM --> Program Tire Size" and chosse a new size, then START, before clicking on NEXT, it give me my previous size applied as Current setting. So, when I process the tire size modification in BCM, it does seems to be written somewhere since it keep my last change, but doesn't seems to be write and the good place since the READ ID in battery section always return me the same size.

Is anybody already saw that problem?

Thanks
 

1500ram12

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Hi guys,

I did try to change my tire size yesterday but it didn't seems to worked. Based of documentation, after applying the change in BCM-->Program Tire Size, after cycle key, I am suppose to get flashing lights in my dash but I didn't have anything light up. I did try to reset the ABS as described in doc but finally, it doesn't seems to have any effect on my speedometer.

One thing strange, in AlfaOBD, when I go in "battery" section to read IDS, in "Vehicule Config 4 --> Dynamic Tire Circumference", it always stay at the same number "2640,00 mm". But when I go in BCM --> Program Tire Size" and chosse a new size, then START, before clicking on NEXT, it give me my previous size applied as Current setting. So, when I process the tire size modification in BCM, it does seems to be written somewhere since it keep my last change, but doesn't seems to be write and the good place since the READ ID in battery section always return me the same size.

Is anybody already saw that problem?

Thanks

Are you trying to enter the size manually or a predetermined size?

Mine is the same way when I check the system ID. There must be a module or part of one that alphaobd can't access to change the setting but doesn't affect anything. I verified before and after changing tire size. I set mine for my 35's that I run in the summer so it's off by about 3 mph now with the 34's I'm running now. (My 35's measures to 34.5 and my 34's are 33.5) I may try and find a happy compromise between the two.


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eraser888

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Are you trying to enter the size manually or a predetermined size?

Mine is the same way when I check the system ID. There must be a module or part of one that alphaobd can't access to change the setting but doesn't affect anything. I verified before and after changing tire size. I set mine for my 35's that I run in the summer so it's off by about 3 mph now with the 34's I'm running now. (My 35's measures to 34.5 and my 34's are 33.5) I may try and find a happy compromise between the two.


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Hi,

Yes, I've tried both way but doesn't seems to change anything. How does this change is suppose to react? Only on analog speedometer, only on Cruse control setting, or both? Currently, my analog speedometer is about 4 km over the cruse control at 100 km. For example, when I set the cruise control at 100km/h, my analog give me about 104 km/h but my real speed (gps verification) is the same than the one I set for cruise control (100 km/h). So, finally, I just need to adjust the analog speedometer.

Thanks
 
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