Software update for fitting of different size wheels/tyres

[James77]

Hi All,

Just wondering, those of you who fit different sizes of wheels for winter or aesthetics do you bother with regular software updates to calibrate the Speedo?

I suspect small changes in circumference do little although the dealer would argue otherwise?!

Thanks

[taylora]

Link provides some numbers on how out your speedo would be.

https://www.autopartuk.com/tyre-calculator/

I'm sure a dealer would say you need to do it and naturally charge for it. I never did on a previous car when I switched from 18s to 16s in winter. I just used my brain, adding 2 or 3 onto the speedo reading wasn't so hard.

[RobQuads]

I expect most people although are changing wheel sizes are also changing tyre sizes such that they are still virtually the same. I am pretty sure Volvo won't be adjusting it for each different set of tyres, they will just be maintaining the overall rolling diameter (within a certain amount of variance).
Provided the speedo is still under-reading they would be fine to this.

[Clan]

Originally Posted by James77

Hi All,

Just wondering, those of you who fit different sizes of wheels for winter or aesthetics do you bother with regular software updates to calibrate the Speedo?

I suspect small changes in circumference do little although the dealer would argue otherwise?!

Thanks

when there is a drastic wheel change the software is updated in relation to maximum lock as well as speedo and safety system calibration , this is often accompanied by mechanical steering lock stops which are fitted in the steering rack . The volvo accessory web site lists the modifications needed for which particular wheel .

[Zebra]

Originally Posted by Clan

when there is a drastic wheel change the software is updated in relation to maximum lock as well as speedo and safety system calibration , this is often accompanied by mechanical steering lock stops which are fitted in the steering rack . The volvo accessory web site lists the modifications needed for which particular wheel .

Agree completely. I went from 275/35R22 to 235/55R19 and did not bother with the software as the smaller wheel size should not cause a problem with the lock whereas going the opposite way might. I did notice speed and MPG change in terms of variation compared to a mobile phone speed measure but not bothered to spend the £50+ that the dealer wanted for software re calibration.

[gaby]

I am not sure if it's a good idea not to have the software updated after a new wheel/tyre combination.
Such a new setup will likely change the behavior of the car. This may cause some safety features
to respond less well if the software is not aware of the actual wheel/tyre setup.

[Quacker]

Originally Posted by gaby

I am not sure if it's a good idea not to have the software updated after a new wheel/tyre combination.
Such a new setup will likely change the behavior of the car. This may cause some safety features
to respond less well if the software is not aware of the actual wheel/tyre setup.

Safety software only measures the speed of the axle relative to any other three axles. That’s whether it is for abs, stability control or any other system including the four wheel drive. It even takes account of the very significant speed differences between sides and front and back while turning a corner at any speed.

Rolling circumference for all approved optional wheel and tyre sizes on the XC90 are within a couple of percent of each other regardless of wheel diameter, so it is not necessary to reprogram the speedometer.