New tyres for XC90 - 20" + Air

[Ringthane]

Originally Posted by Quacker

Don't fit any size that isn't listed in the user manual. All of these will have the same rolling circumference within about 2%. Other sizes will be way out of tolerance and even if they don't interfere with the body, the speedometer will need recalibration to match the new rolling circumference.
[/B]

Not sure what you are saying here. 255/45/20 are standard fit for an Inscription Pro XC60.

[Quacker]

Originally Posted by Ringthane

Not sure what you are saying here. 255/45/20 are standard fit for an Inscription Pro XC60.

If a tyre size and spec is listed as suitable for that model in the manual, then it is fine to fit. If not, and you don't understand what I've written, take expert advice before fitting any tyre or wheel size. Do not assume anything if you do not understand the equivalences and what is needed.
Do not assume that your Volvo dealer even knows. I told my dealer's service manager that I had bought genuine used Volvo 19" wheels and tyres to fit my car[listed below] and he warned me that it might need a speedo recalibration and tyre pressure sensor recalibration. I had already worked out that there would be around 1.5% difference [iirc] and there would be no need for this.

[Ringthane]

With respect, I understand what you have written, but, just to be sure, I went to the User Manual for the XC60, and it says this:

Recommended tyres
On delivery, the car is equipped with Volvo origi- nal tyres that have the VOL1 marking on the side of the tyres. These tyres are carefully adapted to the car. In the event of changing tyres, it is there- fore important that the new tyres also have this marking in order for the car's driving characteris- tics, comfort and fuel consumption to be main- tained.

So, while you may be technically correct, in alerting me to the fact that I need to check that my chosen tyre might be 2% out of spec, from Volvo’s recommended tyre, I would assert that most of us would look at the existing tyre size, either on the car, or in Volvos’s own literature, and go to out tyre dealer, and buy the same.

Given that our existing choice of 255/45/20 tyres is already limited, your warning therefore limits us even more, to Volvo’s recommended tyres.

So, are you suggesting that if I feel that the standard tyres (i.e. the ones fitted to the car from the factory), are too noisy, or don’t grip well in the wet, I can’t replace them with anything other than what Volvo recommends?

[Quacker]

Originally Posted by Ringthane

With respect, I understand what you have written, but, just to be sure, I went to the User Manual for the XC60, and it says this:

Recommended tyres
On delivery, the car is equipped with Volvo origi- nal tyres that have the VOL1 marking on the side of the tyres. These tyres are carefully adapted to the car. In the event of changing tyres, it is there- fore important that the new tyres also have this marking in order for the car's driving characteris- tics, comfort and fuel consumption to be main- tained.

So, while you may be technically correct, in alerting me to the fact that I need to check that my chosen tyre might be 2% out of spec, from Volvo’s recommended tyre, I would assert that most of us would look at the existing tyre size, either on the car, or in Volvos’s own literature, and go to out tyre dealer, and buy the same.

Given that our existing choice of 255/45/20 tyres is already limited, your warning therefore limits us even more, to Volvo’s recommended tyres.

So, are you suggesting that if I feel that the standard tyres (i.e. the ones fitted to the car from the factory), are too noisy, or don’t grip well in the wet, I can’t replace them with anything other than what Volvo recommends?

I have suggested no such thing. Indeed I would take no heed of the VOL1 nonsense. I would recommend that the tyres are marked with either or both 'SUV' or XL or Extra Load on the side though. They recommend all kinds of things, some of which are mainly for their financial benefit, and it takes a bit of knowledge to sort the wheaty information from the chaffy stuff.

[Dirty Rooster]

Originally Posted by Quacker

Hmm! I think probably they will as long as they fit the rim properly and the speedo is calibrated and corrected as necessary to be accurate.

Are you sure that's in the MOT?
I thought acuraccy/operation of the speedo was not part of the MOT.

[Quacker]

Originally Posted by Dirty Rooster

Are you sure that's in the MOT?
I thought acuraccy/operation of the speedo was not part of the MOT.

The speedo must be functional and accurate by law. I've no idea whether they specifically test for accuracy within tolerance at the MOT. They certainly to test that it is functional.
The speedometer must not under-read at all but may over-read by up to ten percent. Therefore all speedometers over-read very slightly from the factory on the tyres fitted, so as to not fall foul of under-reading.
Changing tyre sizes on the 90 series Volvo for the approved available sizes involves up to 2% variation in speedometer readout. However, other sizes that could be fitted but aren't in the standard and optional fitting list may result in a far greater variation in speedometer readout. Which is where expert advice should be sought.

Does that make sense?

By the way, I don't have information as to whether XL rating is a necessity on all other 90 series or any 60 series cars. I do know that this is required on the XC90. Again it is probably explained in the manual or expert advice should be sought if there is any doubt.

[nu11eaf]

If you want smaller wheels and tyres, going from 20" to 19" just increase the tyre profile to give the same circumference/height, without having to calibrate speedo, so going from 275/45/20 to 255/55/19 and Bobs your uncle.

[Quacker]

Originally Posted by nu11eaf

If you want smaller wheels and tyres, going from 20" to 19" just increase the tyre profile to give the same circumference/height, without having to calibrate speedo, so going from 275/45/20 to 255/55/19 and Bobs your uncle.

Yes but there are lots of different widths of 55/19 available and only one has the approximate rolling circumference as 275/45R20.

[nu11eaf]

Originally Posted by Quacker

Yes but there are lots of different widths of 55/19 available and only one has the approximate rolling circumference as 275/45R20.

Volvo use 235/55/19 on the momentum and T8 (wish they would on the Inscription or at least a no cost option) did they used to use 255/55/19 at one time.

[Deman77]

Originally Posted by familymangreg

OK, so have now done a couple of trips on my new Michelin Latitude Sport 3 Acoustic Technology tyres... And..... what a difference! If the car had of been on these from the start, the huge 20" wheel road noise thread I started would probably not exist! To me, they are immediately noticeably quieter.

For those of you who don't know, I had my original Continentals swapped by Volvo/my dealer at 7000 miles to Conti Silents after I complained about the high levels of road noise from the original tyres. I also had the sound deadening b-pillar modification done. I can say with confidence, that changing to the Michelin's has had more of an effect the these other two fixes combined.

To me, what is really apparent is the difference at lower speeds, 30-50mph, where road noise on the Continentals would start to build, you just don't notice that by anywhere near the same degree on the Michelins. And that's not to say they aren't quieter too at other speeds, the difference to me is just most apparent at those speeds. We haven't done any motorway or even particularly fast A roads this weekend either.

I've never had a problem with ride quality, but if I had to note any difference, i'd say the Michelin's again felt a little more compliant. There is no discernible difference in performance.

So, as you might tell, I'm very happy with the Michelins, and without doubt would recommend them over the Conti's any day. Having also been in a new XC90, which I and others have noted has somehow improved levels of noise insulation, I would imagine that a new one, with the Michelins and possibly also the laminated glass would be a pretty refined car on 20" wheels.

:wq

Honeymoon over, are you standing by your original comments? My contisilents came out swapping the winters and I don’t know if it’s the bad storage or just wear in (about 5k from new they had last year) but they are an absolute pig now. Not as dreadful as non-silents but noticeably annoying. I could be convinced to upgrade.