New member and wheels/tyres

[Lexman8]

Hi,

I'm thinking of buying an XC90 and hopefully I'll gather more info from you all over the next few weeks.

I've noticed a few posts about the noise level in the car, particularly from the 20" wheels. I can't stand noisy cars and that's one of the reasons I want to get rid of my CR-V. There's been a lot of discussion on tyre noise over on the Mercedes forum I contribute to and the consensus is that Continental and Pirrelli tyres are very noisy and that the Continentals in particular get stupidly noisy as they wear down. I had Continentals on my Merc CL500 and changed them out for Dunlop Sport Maxx RT. I noticed a significant reduction in noise with the Dunlops as well as a more comfortable ride.

In case anyone doesn't know, the noise levels quoted for tyres use a logarithmic scale so a 3dB reduction is a halving of the (drive-by) noise level. Some examples:

• On 19" wheels, Pirelli Scorpion are rated at 71dB and Dunlop Sport Maxx GT are 68dB. A 3dB difference means the Pirellis produce twice the noise of the Dunlops.
• On 20" wheels, Continental Sport Contact 5 produce 73dB while Goodyear Eagle F1 produce 69dB. So the Goodyears produce less than half the noise of the Continentals.
• Again on 20" wheels but a more extreme example. Continental Cross Contact LS Sport produce 76db (!), more than 4 times the noise of the equivalent Goodyears.

The above figures also demonstrate how much quieter the XC90 with 19" wheels/tyres is compared to the 20" - there's a 2db difference (assuming I've got the tyres correct). Of course there are other factors to take into account (handling, braking, tyre life, etc) but none of the big tyre manufacturers produce a 'bad' tyre. It's down to personal preferences and for me noise and comfort are more important than how quickly I can go round a corner.

Also, these 'drive-by' noise levels don't equate directly to the noise level inside the cabin but are a good indicator.

(For the geeks... There's a difference between sound pressure level (the figures above) and perceived volume because the human ear doesn't 'hear' in a linear way. In other words, in the extreme example above the noise you hear won't reduce to a quarter of its previous level by fitting Goodyears but it should reduce substantially.)