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Discussion Starter · #1 ·
I recently put on four PS2s via Big O Tires (235/40-ZR18)... but some recent postings here about load ratings had me wondering if there were different versions of the PS2 at this size that I needed to worry about whether Big O got the right version?<p>Car is at the dealer right now for several days, so I can't run out to check it ...<p>
 

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Re: Question on Michelin PS2 tires (Helmut Ranff)

I like the PS2's but I just whacked a pot hole and bubbled the sidewall.... <IMG NAME="icon" SRC="http://www.vwvortex.com/vwbb/mad.gif" BORDER="0"> So last night swapped back to my snows at 11 at night. Make sure you get the 95Y.<p>I'm about to give up on 18" wheels/tires - trashed 2 wheels and 3 tires in less than three years.
 

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Re: Question on Michelin PS2 tires (Stan the "R" Man)

I always thought the larger the wheel, the stronger it would be to overcome a pothole. If a pothole is "x" size, a 16" tire would dip into it a whole lot easier than a 18" tire. I'm using these #'s just as examples. A big truck with 30" wheels would glide right over the pothole for example. See my meaning?<p>If this is somewhat correct, why then are the larger tires/wheel combo's exhibiting the opposite reaction? Are the wheels not strong enough and/or the tires not strong enough?<p> <IMG NAME="icon" SRC="http://www.vwvortex.com/zeroforum_graphics/screwy.gif" BORDER="0">
 

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Re: Question on Michelin PS2 tires (Short Circuit)

In the case of the two tire choices on these cars, the outside diameter of the 18" tire should be the same as the outside diameter of the 17" tire. The difference is in the sidewall, which is of course smaller in the case of the 18" tire to allow for the lager rim diameter. As far as potholes, I would estimate that the 17" tire with its larger sidewalls, which are more flexible, is more likely to absorb the impact energy of the pothole in an elastic manner, while the 18" tire, with its smaller sidewall, is more prone to failure.
 

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Discussion Starter · #6 ·
Re: Question on Michelin PS2 tires (Helmut Ranff)

I confirmed they are 95Y PS-2.<p>Had to swap out the PZeros at 14K last week. Noticed that both the front & rear left tires had bubbles on the sidewall. Thought that was a bit strange given I hadn't hit any potholes recently. Then I thought ... my 18 year old son borrowed the R the other night to drive to batting practice because all the other vehicles were low on gas and he was low on time.<p>I asked if he hit a pothole ... he said yup, didn't see it on the freeway off ramp until it was too late ... and he's not used to quick manuevers to avoid potholes since he normally drives an old Tahoe.<p>It was a good excuse to get rid of the PZeros anyway ... but I told him he had to be extra careful with the R and potholes.
 

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Re: Question on Michelin PS2 tires (dawghouse)

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD><i>Quote, originally posted by <b>dawghouse</b> »</i></TD></TR><TR><TD CLASS="quote">It was a good excuse to get rid of the PZeros anyway ... but I told him he had to be extra careful with the R and potholes.</TD></TR></TABLE><p>It's a good excuse to get a four wheel alignment as well. After all, the PS2's are quite $$$ so you don't want premature wear.
 

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Re: Question on Michelin PS2 tires (Short Circuit)

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD><i>Quote, originally posted by <b>Short Circuit</b> »</i></TD></TR><TR><TD CLASS="quote">I always thought the larger the wheel, the stronger it would be to overcome a pothole. If a pothole is "x" size, a 16" tire would dip into it a whole lot easier than a 18" tire. I'm using these #'s just as examples. A big truck with 30" wheels would glide right over the pothole for example. See my meaning?<p>If this is somewhat correct, why then are the larger tires/wheel combo's exhibiting the opposite reaction? Are the wheels not strong enough and/or the tires not strong enough?<p> <IMG NAME="icon" SRC="http://www.vwvortex.com/zeroforum_graphics/screwy.gif" BORDER="0"> </TD></TR></TABLE><p>Your logic would hold true if the outer diameter of the tire increased as the size of the wheel increased. In this case, going from 17's to 18's does not. Otherwise, you couldn't keep the speedo reading the same. <p>If you start with two concentric circles, and keep the outer one the same (OD of tire) but make the inner one bigger (18" wheel versus 17") what is sacrificed? Sidewall. As has been said above, the sidewall is the elastic "padding" that keeps the pothole from hitting the wheel. When you have thinner padding, you it's easier to get wacked.<p>I wouldn't trade my 17's in for 18's even if you gave them too me for free where I live.
 

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Re: Question on Michelin PS2 tires (needsdecaf)

Cafe, I can buy your logic...but explain this: with the stock tires, they stink from all consensus including myself. They had really stiff walls (97 I believe). A softer walled tire seems to tame the car and minimize rear hop (in addition to new alignment specs, etc). So the idea is to get a "softer" rated tire for the S60R, with "stock" sidewall height? Meaning, if comparing 2 tires of the same size spec, but have an option of 91 or 94 rating, the 91 would be the better choice for the S? I'm assuming that the V needs the higher rating tire...<p>Thoughts?
 

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Re: Question on Michelin PS2 tires (Short Circuit)

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD><i>Quote, originally posted by <b>Short Circuit</b> »</i></TD></TR><TR><TD CLASS="quote">Cafe, I can buy your logic...but explain this: with the stock tires, they stink from all consensus including myself. They had really stiff walls (97 I believe). A softer walled tire seems to tame the car and minimize rear hop (in addition to new alignment specs, etc). So the idea is to get a "softer" rated tire for the S60R, with "stock" sidewall height? Meaning, if comparing 2 tires of the same size spec, but have an option of 91 or 94 rating, the 91 would be the better choice for the S? I'm assuming that the V needs the higher rating tire...<p>Thoughts?</TD></TR></TABLE><p>There's the safety factor to consdier as well and I believe Volvo put 95Y on the R due to its weight and potential for high speed driving.<p>According to Pirelli's website:<br>91Y [email protected]<br>95Y [email protected]<p>...and an excerpt from the PDF for PS2's from Michelin:<br>"For high-speed driving, additional inflation pressure and possibly reduced tire loading and/or upsizing is required."<p>LTA<br>
 

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Discussion Starter · #11 ·
Re: Question on Michelin PS2 tires (MagoonR)

Yup ... did that too. Just good hygene plus figured anything that could pop two tires probably didn't help the alignment any.
 

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Re: Question on Michelin PS2 tires (Short Circuit)

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD><i>Quote, originally posted by <b>Short Circuit</b> »</i></TD></TR><TR><TD CLASS="quote">Cafe, I can buy your logic...but explain this: with the stock tires, they stink from all consensus including myself. They had really stiff walls (97 I believe). A softer walled tire seems to tame the car and minimize rear hop (in addition to new alignment specs, etc). So the idea is to get a "softer" rated tire for the S60R, with "stock" sidewall height?</TD></TR></TABLE><br>Load rating is not a measurement of "sidewall stiffness"; that's what's got you confused. It is a measurement of the tire's ability to handle stress, which is a combination of load on the tire, speed, and heat (obviously, these are interrelated). <p>There is more than one way to engineer a tire to handle these things, and different manufacturers take different approaches. So while most higher load-rated tires probably have stiffer sidewalls than most lower load-rated tires, if you compared a collection of similiarly rated tires you'd find a range of sidewall stiffnesses.<p>The PS2s (in my experience with them) have more complance than the Rossos, even when comparing tires with the same load rating.<p><TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD><i>Quote »</i></TD></TR><TR><TD CLASS="quote"> Meaning, if comparing 2 tires of the same size spec, but have an option of 91 or 94 rating, the 91 would be the better choice for the S? I'm assuming that the V needs the higher rating tire...</TD></TR></TABLE><br>91 is not a recommended tire load rating for either S or V, and it has nothing to do with ride quality or the "hop". They are not considered safe because within the normal operating envelope of the vehicle there is too high a risk of tire failure.<p>That said, driving either an S or V below maximum vehicle load in the United States -- where cruise speeds are going to be way below the car's potential -- is probably doable with 91. But I see no point in taking the risk. I can see your insurance company not paying for damages due to a high speed blowout if they found you knowingly put under-rated tires on the car.
 

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Re: Question on Michelin PS2 tires (mgotts)

I believe Volvo puts a high load rating on the tires because of the potential of towing something.
 

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Re: Question on Michelin PS2 tires (mgotts)

It's the combination of things that count.<p>If you're going to run a 91 rated tire at 30 psi and go 120mph with a carload of passengers, you're gambling. Ford learned this the hard way.<p>But I doubt you'll have those same risks running at 37-39 psi on a 91 with just the driver aboard.
 

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Re: Question on Michelin PS2 tires (Short Circuit)

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD><i>Quote, originally posted by <b>Short Circuit</b> »</i></TD></TR><TR><TD CLASS="quote">Cafe, I can buy your logic...but explain this: with the stock tires, they stink from all consensus including myself. They had really stiff walls (97 I believe).<p>Thoughts?</TD></TR></TABLE><p>As Mgotts has correctly pointed out, load rating does not necessarily mean stiffer sidewas. In some cases, it might, but not necessarily. <p>Again, as Mgotts said, different tire manufacturers construct their tires in different ways, and the construction of the sidewall bands is certainly a very key design element. It will have major, major implications on how the car rides, how it handles bumps, how it corners, etc. Higher load rating tires have a more robust construction, but that does not mean that they are necessarily stiffer in the sidewall. Remember, heat is the enemy of the tire. Overloading a tire, either by running it for a sustained time at a higher speed than it is rated for, or running it for a sustained time at a higher load than it is rated for will cause the tire to become overheated, and the tire's construction to start to fail. <p>For the case of the rear hop, it seems that the 4C is very sensitive to how the sidewall deflection affects the accelerometers and therefore the damping. In the case of the PZero, it seems to be a poor match. <p>As for your discussion regarding pothole performance, don't forget that air is what holds your tire up (and therefore your car). Realy, the air is what is the buffer, not the sidewall. If the sidewall was that stiff, it could hold the car up on it's own (i.e. runflat tires). In my discussion above, I taklk about losing tire sidewall height, but what you are really losing is air space. Therefore, when you lose more air space, regardless of sidewall stiffness, you lose padding. This is also why runflat tires have been described as having a "brittle" ride, and are hard to tune the suspension for if both runflats and regular tires are used on the same vehicle (E46 3 series is an example). <p>So really, when you're talking about trying to achieve more "comfort", the load rating is not where to look. You really have to understand how the manufacturer constructed the tire. For instance, the Michelin Pilot Sport All Season has a load rating of 93Y. The less aggressive Pilot Exalto All Season has a load rating of 94H. And I'd be willing to bet that the Exaltos have a slightly softer sidewall flex.
 

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Re: Question on Michelin PS2 tires (needsdecaf)

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD><i>Quote, originally posted by <b>needsdecaf</b> »</i></TD></TR><TR><TD CLASS="quote"><p>For the case of the rear hop, it seems that the 4C is very sensitive to how the sidewall deflection affects the accelerometers and therefore the damping. In the case of the PZero, it seems to be a poor match. <br></TD></TR></TABLE><p>So, is there any way other than actually buying tires and driving on them to know if their sidewall compliance will be of the sort that WILL interact better with 4C? That is, any way to predict this before buying, based on information a consumer would have access to?
 

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Re: Question on Michelin PS2 tires (kenschel)

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD><i>Quote, originally posted by <b>kenschel</b> »</i></TD></TR><TR><TD CLASS="quote"><p>So, is there any way other than actually buying tires and driving on them to know if their sidewall compliance will be of the sort that WILL interact better with 4C? That is, any way to predict this before buying, based on information a consumer would have access to?</TD></TR></TABLE><p>I think THIS is the best place for that kind of info. Many Swedespeed members have said PS2's go a long way at fixing the rearend hop (I'm one of them, it's like night and day for Sport and Advanced mode, in Comfort mode it didn't seem to help much). Other members have had similar experience with the new Goodyear F1's (I think that's the model) and other tires, do some searches.<p>LTA<p>
 

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Re: Question on Michelin PS2 tires (LTA)

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD><i>Quote, originally posted by <b>LTA</b> »</i></TD></TR><TR><TD CLASS="quote">I think THIS is the best place for that kind of info. Many Swedespeed members have said PS2's go a long way at fixing the rearend hop (I'm one of them, it's like night and day for Sport and Advanced mode, in Comfort mode it didn't seem to help much). Other members have had similar experience with the new Goodyear F1's (I think that's the model) and other tires, do some searches.<p>LTA</TD></TR></TABLE><p>I agree, word-of-mouth and anecdote help, but there is also alot of subjectivity here (some people don't even notice their car's sidehopping, etc)...so I'm looking for a little more rational understanding of how we could predict that a given tire with given features would perform with 4C
 

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Re: Question on Michelin PS2 tires (kenschel)

Moose-<p>I think the bump steer issue is really always there if 4C is there. I do not<br>think tires or pressure help too much. <p>People may say things and have theories and they may help but the truth it is that 4C is unpredictable just as are road irreguaritiy so each time Mr. Bump and Mr. 4C meet you never know what will happen.<p>I have had the car sound as though it was going to explode and crash going over a routine manhole cover that in my 850 at most would produce ABS pulsation, nothing ever as harsh as 4C which acts as a hydraulic jack hammer or pile driver
 

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Re: Question on Michelin PS2 tires (Helmut Ranff)

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD><i>Quote, originally posted by <b>Helmut Ranff</b> »</i></TD></TR><TR><TD CLASS="quote">Moose-<p>I think the bump steer issue is really always there if 4C is there. I do not<br>think tires or pressure help too much. <p>People may say things and have theories and they may help but the truth it is that 4C is unpredictable just as are road irreguaritiy so each time Mr. Bump and Mr. 4C meet you never know what will happen.<p>I have had the car sound as though it was going to explode and crash going over a routine manhole cover that in my 850 at most would produce ABS pulsation, nothing ever as harsh as 4C which acts as a hydraulic jack hammer or pile driver </TD></TR></TABLE><p>True but the different tires move the "sweet spot" up or down the speed band so to speak.<br>Tire X will show the bump at 60 while the other will only do so at 80 or 90. At that point with the higher or lower speed the bump will be less pronounced. But yes, it will remain. No way to really get rid of it.
 
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