50 or 55 profile Tyres

[Skep]

Has anyone fitted 50 or 55 profile tyres instead of the 275/45r20 on an R Design or any other 20" wheel? My factory fit continentals are coming to the end of their life and wondering if a bigger profile side wall might help the road noise and make it a little softer on the pot holes.
Suggestions also welcome of brands to fit next that have been tried and tested and quieter/comfier.

Skep

[gaby]

Will a /55 fit? The diameter will be 7.4% more (31.9" - 29.7") than a /45.

[Skep]

This is what I'd like to confirm, I did look, although quite a while ago at the difference in circumference between the 45/50/55, from what I recall the 50 was similar to a 22" wheel, but wondered if there would still be a bit of space. To be safe I think I'd try a 50 if no one comes back and say they've tried and failed.

[Driver Dave]

Surely if you put on a larger diameter tyre your speedo will be inaccurate and need to be recalibrate.

[electrocoolman]

Many tyre websites have calculators for rolling radius equivalent sizes, so speedo readings remain sensible. You might have to downsize from a 20" to 19"or 18" in order to change the profile. Although there is a cost in new rims, the smaller tyres can be cheaper, which offsets the price of the rims.
Had 18" 40 profile on my car originally, and as stated, noise and uncomfortable ride were factors in changing to 17" 50 profile tyres. Currently running on Michelin Cross climate.
Low noise and comfortable ride.

[gaby]

I don't know the legal regulations in the UK, in Belgium only wheel/tyres sizes are allowed that
are mentioned in the conformity document (or the owners manual?) of the car. For the XC90,
all sizes result more or less in the same diameter and there is only one size for 20" wheels.

[Lexman8]

Originally Posted by gaby

I don't know the legal regulations in the UK, in Belgium only wheel/tyres sizes are allowed that
are mentioned in the conformity document (or the owners manual?)

I'm fairly sure it's the same in the UK. In any case, you'd have to inform your insurer of the change and they may take a dim view of it. If you don't inform them it may invalidate your insurance.

[Rooster]

Why not just use a tyre that has a softer sidewall on it,

I've noticed a few xc90's starting to come through with Pirelli tyres on rather than the conti's, maybe there's a reason,

Also tyre pressures seem to affect ride quiet abit on the cars with bigger wheels on

[NewVolvo]

After speaking to a friend of mine (who used to work with tires), he reckons that Michelins are not only the best tire to have, but it also gives a nice soft, quiet drive. Downside is that they have a softer compound than say, Pirellis but dont actually wear out that fast. I did 50k on Michelins in my previous A6 and after 50k still had 4mm left. Amazing! Especially so as I wasnt hanging about......

[nu11eaf]

Originally Posted by Skep

Has anyone fitted 50 or 55 profile tyres instead of the 275/45r20 on an R Design or any other 20" wheel? My factory fit continentals are coming to the end of their life and wondering if a bigger profile side wall might help the road noise and make it a little softer on the pot holes.
Suggestions also welcome of brands to fit next that have been tried and tested and quieter/comfier.

Skep

To go to 55 you will need to go to 19"" rims to maintain the same diameter. Best option is to buy a set of 19" wheels and tyres. Several people selling them nearly new after fitting larger wheels. Look on ebay or Google. It will be the cheaper option than buying tyres and rims separately.
But make sure they are for MK2 XC90 and correct tpms system, newer models do not have the tpms valves