Topic:New tires 17in Volvo C70 Conv HT
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T O P I C     R E V I E W
KolaskeIt's time for me to replace my 225/45R17 91Y Pirelli P6000 tires. I would like to change to ones that are more durable and reasonably price. Or at least a better value for the money than Pirelli.
Also, while trying to educate myself a little more about tires, I have come to the conclusion that Volvo's decision to put Y rated tires on this car are completely unnecessary. Wouldn't a Z or even a V rated tired be sufficient?
Help me please.

[This message has been edited by Kolaske (edited February 07, 2003).]

[This message has been edited by Kolaske (edited February 07, 2003).]

CapriRacerLook at the chart below:

Speed Rating....Max Speed
.....Z...........over 150

(I hope you'll excuse the dots, but this software takes out excessive spaces and makes the chart look really funky.)

That was what the chart looked like for many years. The purpose of the Z rating was to be provide a place for specialty tires where the speed capability of the tire was matched to the speed capability of the vehicle and it was to be such that a given vehicle took a given tire size and vice versa, so there could be no mixup.

But because there was a pretty big gap between S and H, and because there were too many vehicles capable of over 150, it was recently decided to add:


Now what to do about Z? Can't change it because you have to "grandfather" all the old specs. Solution: Leave Z right where it is - opened ended and suggest that all tire manufacturers adopt W and Y ratings and use Z only when they can't use W and Y.

This is a long way of saying Z is still the highest rating, even though it doesn't appear that way.

Another long winded explanation:

The reason Volvo put Y rated tires on the vehicle is 1) so they could qualify the vehicle in other countries that don't have top speed restrictions without having to change the type of tire and therefore redo the springs, shocks and sway bars. and 2) a higher speed rating is an increased safety margin.

Hope this helps.

[This message has been edited by CapriRacer (edited February 07, 2003).]

KolaskeThank you for your reply.

I am already familiar with the alphabetical ratings and their numerical equivalents. And the fact that W and Y were created after Z.

You did kind of answer my question about Volvo' reason for choosing Y, which makes sense.

But I am unclear on a little bit of it. Are you saying that it would not be wise for me to go to a lower rated tire due to the design of the car (springs, shocks, etc...)?

Even though the car is capable of higher speeds, mine will not be seeing anything over 100mph and probably not even that. My days of driving fast are long past.

Thanks again.

CapriRacerDropping the speed rating from a W to a V is probably not going to affect the handling much at all. You could probably go to an H with only a slight difference.

Dropping into the T and S range is probably not a good idea (and I doubt anyone make a 45 series in an S or T rating anyway.)

Each of these steps down are going to mean a proportionally softer ride, some loss of grip, and less steering crispness.

Hope this helps.

KolaskeYes, thank you!

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