Wheel Change

[Crockers]

Originally Posted by Director76

That sounds like a recipe for trouble - that’ll get you moving for sure but you’re running the risk of a loose back end under steering or braking due to uneven grip.

Totally agree. Just using winters on the front is tantamount to suicide. Your back end will soon become your front.

[SuffolkBoy]

I dont think your Insurance company would be too pleased either if you have an accident - you might find that you insurance is invalidated by only fitting winter tyres to the front axle.

[NewV90Owner]

Tyre wear changes circumference. Circumference = pi x diameter.

If your tyre starts with 8mm of tread and you change at 2mm that is 6mm x 2 = 12mm.

Change in circumference = 3.14 x 12 = 37.68 mm (3.768 cm).

How does the car know how worn the tyres are?

Circumference will also change with load, pressure and temperature. It's all these things that make speed calculations from wheel revolutions very difficult and manufacturers err on the side of caution.

If the overall circumference and the offsets are all in the spec then I don't see why it needs a software change.

[gaby]

Isn't this (alleged) problem specific for a wheel change from (or to?) 22"?

[Haldex]

From the manual:

"Contact an authorised Volvo workshop for updating the software at each change of tyre dimension. A software download may be necessary both when changing to larger and smaller dimensions, and also when switching between summer and winter wheels."

But then again- I don't think not doing a software update will have any effect except perhaps on the odometer/speedo..

[MaDProFF]

Originally Posted by S90

As I’m only front wheel drive I’m just getting two fronts, pretty sure they’re Nokian, £175 each fitted for 255/35 R20, I think that’s the size my current tyres are. Sod’s law states that we will see not a drop of snow for the next 2 yrs!!

This is a joke? Trying to wind us up? if not:-

One word ABS the best thing about winter tyres is you stop when you brake, only fit 2, and ABS and braking is not going to stop you. it is a recipe for disaster, and INSURANCE if they inspect the car or police you are in trouble, infact it is probably illegal. (in UK)

Also if you are using a Tyre Fitter I cannot believe they would actually do this.

[Quacker]

Originally Posted by MaDProFF

This is a joke? Trying to wind us up? if not:-

One word ABS the best thing about winter tyres is you stop when you brake, only fit 2, and ABS and braking is not going to stop you. it is a recipe for disaster, and INSURANCE if they inspect the car or police you are in trouble, infact it is probably illegal. (in UK)

Also if you are using a Tyre Fitter I cannot believe they would actually do this.

Professional tyre fitters who go by the book, even when fitting two new matching pattern tyres to the two worn, will only fit the grippiest tyres on the back, no matter which wheels are the driven ones. Front end slide is far easier to control than the rear end letting go.

I certainly would not put snow tyres on only one axle and certainly not the front only.

[Bendolfc]

Originally Posted by S90

As I’m only front wheel drive I’m just getting two fronts, pretty sure they’re Nokian, £175 each fitted for 255/35 R20, I think that’s the size my current tyres are. Sod’s law states that we will see not a drop of snow for the next 2 yrs!!

Don't do it, you should always have the best tyres on the rear is the usual advice as most drivers can correct the front going but won't be able to do anything if the rear steps out.

With winters of the front there is a good chance in snow you will steer into as bend, keep traction on the front and the back will step out and there will be nothing you can do about it.

[Lexman8]

Originally Posted by Zebra

So my question is, is the software reset just the slight change in circumference and so I can just ignore it or is there something I am missing?

I'm fairly sure a TPMS re-calibration is all that's needed.

Look at the attached table; there's only a 1.4% difference in the important parameters and the speedo will still be within the allowed tolerance.

I swap between 19" (summer) and 18" (winter) twice a year without any issues.

(I think the dealer is having a laugh.)
_

[Lexman8]

Originally Posted by S90

As I’m only front wheel drive I’m just getting two [winter] fronts

Not a good idea for all the reasons above.