New wheels/tires/springs - error?

[svtraid]

Hey everyone, first post on the forum, but been following for a while... not sure if this has been discussed, but when installing 20” wheels/tires and lowering springs, the A90 pops up tire size and chassis messages. I’m sure the guys at Titan and Induction have seen it. Is this some we can clear/set ourselves? Any input is very appreciated!

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[s219]

How about a photo of the messages? This is surely something we've dealt with on the BMW side before.

 

[svtraid]

How about a photo of the messages? This is surely something we've dealt with on the BMW side before.

thanks for the quick reply!

the message is “continued driving possible: chassis". i’m pretty sure due to the H&Rs...

for the tire settings, i left it at custom 19”/275 and the tpms synced up. that message went away. i’ll upload a pic in a few

 

[svtraid]

thanks for the quick reply!

the message is “continued driving possible: chassis". i’m pretty sure due to the H&Rs...

for the tire settings, i left it at custom 19”/275 and the tpms synced up. that message went away. i’ll upload a pic in a few

here you go...

 

[s219]

So the TPMS message is usually related to the iDrive display where it shows you the recommended pressure next to the actual pressure. To do this it has to know what tire setup is on the car, and it usually gives stock options, as well as an option to "train" the system to a reference cold pressure if you don't have one of the stock tire combos. This is purely about that iDrive display and won't affect any functionality at all. The TPMS system learns new sensors by a different process.

Regarding the chassis warning, you might want to carefully examine the shocks/struts on all corners to make sure the wiring for the adaptive suspension wasn't disconnected or damaged. This controls the damper rate when you select driving mode. I have heard of cases where the wire gets disconnected or damaged when doing suspension work and it triggers a chassis message. Can't say if it's the same one, but it's a likely guess if you just were in there installing lowering springs. I assume you kept the stock shocks and struts, correct?

 

[svtraid]

So the TPMS message is usually related to the iDrive display where it shows you the recommended pressure next to the actual pressure. To do this it has to know what tire setup is on the car, and it usually gives stock options, as well as an option to "train" the system to a reference cold pressure if you don't have one of the stock tire combos. This is purely about that iDrive display and won't affect any functionality at all. The TPMS system learns new sensors by a different process.

Regarding the chassis warning, you might want to carefully examine the shocks/struts on all corners to make sure the wiring for the adaptive suspension wasn't disconnected or damaged. This controls the damper rate when you select driving mode. I have heard of cases where the wire gets disconnected or damaged when doing suspension work and it triggers a chassis message. Can't say if it's the same one, but it's a likely guess if you just were in there installing lowering springs. I assume you kept the stock shocks and struts, correct?

very much appreciated! you’re correct, I kept the stock shocks and struts, only installed the springs. i was afraid that damage to the wire/sensor could’ve been it... hopefully it’s just disconnected.

 

[svtraid]

update... so, checked the suspension and electronics all the way around, luckily no damage seen, and nothing apparently disconnected. there was another forum member that replied something regarding front to rear wheel/tire size ratios. could it be he’s right? the slight change in ratio is throwing the TC and VSC systems off?

The wheels/tires are f: 265/30/20 r: 295/30/20. would it be that sensitive?

 

[kona61]

update... so, checked the suspension and electronics all the way around, luckily no damage seen, and nothing apparently disconnected. there was another forum member that replied something regarding front to rear wheel/tire size ratios. could it be he’s right? the slight change in ratio is throwing the TC and VSC systems off?

The wheels/tires are f: 265/30/20 r: 295/30/20. would it be that sensitive?

Yes, that’s likely why. they need to be the same size otherwise the car is always reading the incorrect speeds for the ESC, ABS, etc

 

[svtraid]

Yes, that’s likely why. they need to be the same size otherwise the car is always reading the incorrect speeds for the ESC, ABS, etc

well... guess it’s down to 285/30 we go

 

[kona61]

well... guess it’s down to 285/30 we go

Use a tire calculator to get as close to the original wheel/tire diameter as possible.

 

[svtraid]

Use a tire calculator to get as close to the original wheel/tire diameter as possible.

did just that... 285/30 is 3mm diff, 295/30 is 10mm. who knew? not I! the front is a about 6mm difference.

 

[kona61]

did just that... 285/30 is 3mm diff, 295/30 is 10mm. who knew? not I! the front is a about 6mm difference.

Now I will note, the size of the tires do not matter. If you increased both so that the angular velocity remained the same, the car would not know the difference. However, I don't want to do calculation right now, but the easiest path would be to simply find a wheel/tire setup that maintains its size as close as possible to the stock setup.

 

[svtraid]

Now I will note, the size of the tires do not matter. If you increased both so that the angular velocity remained the same, the car would not know the difference. However, I don't want to do calculation right now, but the easiest path would be to simply find a wheel/tire setup that maintains its size as close as possible to the stock setup.

got it. do you think the H&R springs would also play a part? being that they drop the front .25” lower than the back?

 

[kona61]

got it. do you think the H&R springs would also play a part? being that they drop the front .25” lower than the back?

No, unless the car really dislikes being lowered for whatever reason.

 

[s219]

I feel like a tire diameter mismatch would trigger ABS/VSC/TPMS errors (or limit driving dynamics) more than throwing a chassis error. Do you have a way to read the specific error code? That would narrow it down considerably.

Run the math on the diameter differences from stock and between front and rear (both stock and new). What is the % diameter difference?

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