XC90 Winter Tyres Q's

[Lexman8]

Originally Posted by ergonomist

I have an MY16 Inscription. Got a reasonable deal on Volvo 19" rims plus pirelli scorpion winter tyres and TPMS sensors. Now had two winters with them - each time I just swap wheels and press the calibration button on sensus. All seems to work - reports tyre pressures as it should.

Interesting as this implies that the car can store pairing info for more than one set of sensors. It's strange that Volvo say that dealer setup is required but perhaps this is only for the first time that new sensors are fitted.

To be clear, have you seen it report different pressures after swapping? (Rather than just displaying the previous set of pressures that were obtained from the last set of 'valid' sensors.)

[Philip Fisher]

Originally Posted by Lexman8

Interesting as this implies that the car can store pairing info for more than one set of sensors. It's strange that Volvo say that dealer setup is required but perhaps this is only for the first time that new sensors are fitted.

To be clear, have you seen it report different pressures after swapping? (Rather than just displaying the previous set of pressures that were obtained from the last set of 'valid' sensors.)

Perhaps they dont have an individual code per vehicle, just a code per sensor. So all OSF sensors on all XC90s transmit on the same code and so on? The transmission is so low power I cant imagine adjacent cars interfering....?

[Director76]

The later cars, mine included, don’t use sensors on the wheels but the cheaper ABS sensor based system. Doesn’t give you an accurate reading to 0.1 bar on the press of a button like my last 2 x Touaregs 😐

[Lexman8]

Originally Posted by Philip Fisher

Perhaps they dont have an individual code per vehicle, just a code per sensor. So all OSF sensors on all XC90s transmit on the same code and so on? The transmission is so low power I cant imagine adjacent cars interfering....?

Yes, it's possible and this left me wondering how the car could identify which sensor is on which wheel so as to give appropriate readings.

A bit of Googling later...

It seems that the latest dTPMS systems use multiple antennas in the car to allow them to automatically identify which sensor is where. Previously, it was necessary for a sensor to be location-coded by a dealer. Obviously, we don't know if Volvo uses a self-identifying system but presumably a dealer could tell us. Assuming it does, then swapping wheels/tyres should be simple. (However, this doesn't explain why my mate with the XC90 was told otherwise, unless the Volvo system is the older 'dumb' type or the dealer got it wrong which is distinctly possible.)

Also, if it is self-identifying, this would make tyre rotation much simpler. I like to rotate the tyres front to back at each summer/winter swap to even out the wear. This avoids the potential problem of having to replace 2 worn tyres on just one axle and thus having significantly different tread depths on the two axles. Having said that, as far as I can tell, there isn't a big difference in XC90 tyre wear on the two axles anyway.

[Philip Fisher]

Tyre rotation, hadnt thought of that. I rotated my tyres a couple of months back. I am not even sure that I clicked recalibrate and everything just seemed to work.....

[Lexman8]

Originally Posted by Philip Fisher

Tyre rotation, hadnt thought of that. I rotated my tyres a couple of months back. I am not even sure that I clicked recalibrate and everything just seemed to work.....

You might be in luck then in which case a second set of wheels with their own sensors might be okay.

[ergonomist]

Hmm... Not sure I've ever checked whether the reported pressures change. I 'think' they do (I tend to have to re-inflate the stored tyres after they've been off the car for a few months). Dealer supplied the winter wheels and tyres, but didn't fit them - so I did the initial calibration using sensus. The reported pressures always feel about right (and do vary from day to day). And I also rotate my wheels front to back when I swap them and, again, not seen any strange reported pressures. I've just assumed that the low power of the TPMS sensors means that they're only detected by the adjacent wheel sensor.

Remind me, and I will check the pressures in November when I swap them again!

[AB-UK]

You say the pressure "feel about right".
Can you check them manually too?

[ergonomist]

Sorry - careless wording. What I meant was that the reported pressures are in line with what I expected, eg obtained with a handheld pressure gauge when I inflated the tyres, and also they vary as I expect (eg when parked in the sun, the tyres on the sunny side can be 1-2 psi higher than the shaded side for the first mile or two). And before you ask, no - I don't spend the whole journey inspecting my tyre pressures So even if they're not quite accurate from one set of sensors to another, they're certainly seem to be within a psi or two of what they should be.