Tyres, wrong ones??

[asteward71]

Had the XC90 three months now. All spot on so far.

However it came fitted with some very obviously fat 255/55/18 tyres. They do stand out a little and I'm not convinced about the impact they have on fuel economy.

Anyway the front ones need replacing and I'm thinking about replacing all four with what I understand are the standard 235/60/18. The rear ones have tonnes of life in them however, so the other option is to stick with the wider ones and replace the front ones with 255's again for now. The third option is to simply put 235's on the front and retain the 255's on the rear.

I guess what I'm wondering is has anyone heard of 255's being used on an XC90? are they safe? Also can you run 235's on the front and 255's on the rear? I previously ran a BMW with considerably wider rear tyres than the front, but the alloys were also wider.

For the record the alloys are the standard 18inch ones.

Any advice welcomed.

[Gixxer Rolle]

Here can you calculate and compere different tyres zize

http://www.miata.net/garage/tirecalc.html

Bad thing with wider tires:
Higer fuel consumption.
Higer risk of aquaplaning.
Expensive.

If you have wider tyres at rear the car will be understeered.

[mca]

I dont think its wise to mix tyre sizes on an XC90. Firstly, the AWD system doesn't appreciate a significant difference in wear between front and rear tyres of the same size, so I'm not sure what damage will be done by running two completely different sizes of tyre front and rear.

Secondly, the handling will be compromised from what was intended by Volvo.

And thirdly, are you sure that the width of the alloy rim can really safely accommodate the 255 width tyre that you currently have? I too ran BMWs, before my XC90, but generally the staggered rear tyres where only fitted by BMW to larger rear wheels and only on rear wheel drive cars.

I think in order to preserve the AWD mechanism's workings and safety you should consider now a good time to replace all four tyres with the standard size.

[yeoman]

Originally Posted by asteward71

Had the XC90 three months now. All spot on so far.

However it came fitted with some very obviously fat 255/55/18 tyres. They do stand out a little and I'm not convinced about the impact they have on fuel economy.

Anyway the front ones need replacing and I'm thinking about replacing all four with what I understand are the standard 235/60/18. The rear ones have tonnes of life in them however, so the other option is to stick with the wider ones and replace the front ones with 255's again for now. The third option is to simply put 235's on the front and retain the 255's on the rear.

I guess what I'm wondering is has anyone heard of 255's being used on an XC90? are they safe? Also can you run 235's on the front and 255's on the rear? I previously ran a BMW with considerably wider rear tyres than the front, but the alloys were also wider.

For the record the alloys are the standard 18inch ones.

Any advice welcomed.

Very importantly, Heaven forbifd you are in an accident.The police could charge you for making unauthourized modifications to your car( or what ever terinology they chose) and secondly, you insurers will probably not pay out as different tyre sizes goes against the manufacturers recommendations.You could be hit with claims for personal liability in excess of hundreds of thousands of pounds!!

[Jim314]

Just change all four to the proper 235/60-18s. You could try getting the tyre shop to give you a break on the price of new tyres because they can resell the two lightly worn 255/55-18s.

[RoyMacDonald]

Originally Posted by Jim314

Just change all four to the proper 235/60-18s. You could try getting the tyre shop to give you a break on the price of new tyres because they can resell the two lightly worn 255/55-18s.

Or ebay them. I got £230 for 2 lightly worn ones and 2 worn ones

[chunderground]

try black circles - usually good price - good service and fitters
I would change them all without a doubt

[stuarthartley]

yes can only advise that you change all four as the profiles that you have given will send the speedo out as well and they sound to much for the rims, if it was my car i would change all four just for peace of mind

[GJB]

Try pneus on line as well may give a very good price

[mca]

From page 122 of the owners manual :

Your car is fully approved, which means that
you may not deviate from those dimensions and
performance ratings indicated in the vehicle
registration.

Follow these rules carefully in order to
replace tyres with tyres of the same type; radial
tyres, tyre dimension and designations should
be the same.

Ideally, the tyres should be of the
same brand or there is a risk that the car’s
driving characteristics may be altered. Check
with your dealer regarding which sizes are
available for your car.

NOTE! This is extremely important for allwheel
drive models (AWD) since even small
size differences can cause transmission
damage.