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Discussion Starter · #1 ·
I have not searched for this simply because I don't know what to search for. In fact, I am not sure I know how to describe it either.<p>Many times, when my car goes over a puddle or almost any type of relatively big bump, if I am going fast enough, the impact is quite significant and it feels as if it went as far as hitting the wheel. The first times this happened to me, I actually got out of the car, afraid I had bent the wheel or damaged the tire. Now, I just try and ignore it, but it really bothers me and I can't help but feel I am damaging something.<p>I am assuming that, since this is such a low-profile tire, this is exactly what's happening in these cases: that the wheel is getting impacted as it is very close to the ground.<p>Am I right? And if so, doesn't this damage the wheel and also the tire? Any way to avoid this?<p>By the way, I usually keep my tires inflated at around 40-41 psi.
 

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Not sure if you have OEM 17" or 18" Pegasus wheels, but this sounds normal for a 40-41psi inflated tire. Is that cold or hot tire pressure? Expect the air pressure to increase as much as 3 psi as it warms up. <p>Sounds like you might want to consider the 3RD EYE TPMS system to keep an eye on things <IMG NAME="icon" SRC="http://www.vwvortex.com/vwbb/smile.gif" BORDER="0"><br><A HREF="http://www.vivaperformance.com/parts/catalog/product_info.php?products_id=338" TARGET="_blank">http://www.vivaperformance.com...d=338</A>
 

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Discussion Starter · #3 ·
Re: (George @ ViVA)

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD><i>Quote, originally posted by <b>George @ ViVA</b> »</i></TD></TR><TR><TD CLASS="quote">Not sure if you have OEM 17" or 18" Pegasus wheels, but this sounds normal for a 40-41psi inflated tire. Is that cold or hot tire pressure? Expect the air pressure to increase as much as 3 psi as it warms up.</TD></TR></TABLE><p>OEM 18" Pegs<br>40-41 psi hot
 

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Re: (Razor1973)

Run them at 37 psi all the way around. I felt a big difference in the comfort of the ride in all settings. Also if you ditch the pirellis you will feel even more of a difference. Those things should be labled "your beautiful car comes stock with rocks for tires. Sidewalls are terrible. <IMG NAME="icon" SRC="http://www.vwvortex.com/vwbb/eek.gif" BORDER="0">
 

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Discussion Starter · #5 ·
Re: (MASH)

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD><i>Quote, originally posted by <b>MASH</b> »</i></TD></TR><TR><TD CLASS="quote"> Run them at 37 psi all the way around. I felt a big difference in the comfort of the ride in all settings. Also if you ditch the pirellis you will feel even more of a difference. Those things should be labled "your beautiful car comes stock with rocks for tires. Sidewalls are terrible. <IMG NAME="icon" SRC="http://www.vwvortex.com/vwbb/eek.gif" BORDER="0"> </TD></TR></TABLE><p>In past posts, several people have suggested that I keep my tires inflated at 2-3 psi above Volvo's suggested pressure when I complained about body roll. It made a big difference.<p>So now I should keep them below Volvo's suggestion so that I don't feel these bumps as much?<p>My beautiful car comes stock with rocks for tires, an overly soft suspension and lifeless steering to boot.<p>No manufacturer should be able to afford these "imperfections" in their bread & butter sports model. Good engine, great suspension, amazing tires and a good communication with the road should be paramount in these cars.
 

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Re: Big wheel/tire impact in large bumps - Why? (Razor1973)

It almost sounds like the 4C is not working for you at all. Is this something that just exhibited itself, or has it always been this way? If you change the 4C buttons, do you notice any difference?<p>Might be simply a SUM download/update is all you need to get things back to normal - that's what I'd suggest to you, other than taking it one step further and checking out the front shocks itself for leaks, etc which they ought to do when you take it to the dealer....
 

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Discussion Starter · #7 ·
Re: Big wheel/tire impact in large bumps - Why? (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">It almost sounds like the 4C is not working for you at all. Is this something that just exhibited itself, or has it always been this way? If you change the 4C buttons, do you notice any difference?<p>Might be simply a SUM download/update is all you need to get things back to normal - that's what I'd suggest to you, other than taking it one step further and checking out the front shocks itself for leaks, etc which they ought to do when you take it to the dealer....</TD></TR></TABLE><p>It has always happened and it happens in all three modes. Is this an indication of something?<p>I am taking the car in for its first scheduled maintenance soon. I will make sure I mention this to them. I wasn't going to, as I thought this was just the way this tire configuration would work for this car and everybody experienced the same problem, which wasn't really a problem, just seemed like one.<p>Thanks for the heads up.
 

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Re: (Razor1973)

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD><i>Quote, originally posted by <b>Razor1973</b> »</i></TD></TR><TR><TD CLASS="quote"><p>OEM 18" Pegs<br>40-41 psi hot</TD></TR></TABLE><p><br>Hi Razor,<p>I had my checked my tires after 6 hard laps around a local track here in England. What I measured was:<p>L and R Front - both 41 psi<br>and <br>L and R Rear - both very close to 40.5<p>All tires were set to 36 before I left for the track, but I still noticed some evidence of heavy rolling on the edges of the tires, not the side wall, but edges as it was on the limits of the tread and looked excessive.<p>I was recommended that I use 45 psi hot and I certainly believe it after my track day. This may be particular from tire to tire, but I seriously think what I had set for "hot" temps was too low and will definately raise the psi next time.<p>Kevin <p>Note: written with Nurburg on my mindand trackday, so when I meant hot, I meant <I>hot.</I> <BR><BR>
<i>Modified by KVB at 2:39 PM 3-17-2006</i>
 

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Re: Big wheel/tire impact in large bumps - Why? (Razor1973)

I think I've experienced what you were describing . . . fwiw, my tires are generally at 37 to 39 psi (upper half of Volvo's recommended range).<p>I've felt really harsh impacts even from obstacles that don't seem that large. For example, when coming upon a new layer of asphalt that sits an inch or so above the older pavement that I'm driving on. The front end really feels like it is crashing into a bump.<p>My interpretation is that it is actually the 4C over-reacting, & stiffening up the shock damping too much. It is not just due to the stock tires alone, because it also happens with my winter tires that are only V-rated.<p> - Mark
 

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Discussion Starter · #10 ·
Re: (KVB)

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD><i>Quote, originally posted by <b>KVB</b> »</i></TD></TR><TR><TD CLASS="quote">I was recommended that I use 45 psi hot and I certainly believe it after my track day. This may be particular from tire to tire, but I seriously think what I had set for "hot" temps was too low and will definately raise the psi next time.</TD></TR></TABLE><p>I see... But someone was suggesting the opposite: that I deflate my tires to avoid these impacts.<p>I shall try the 45 psi hot and see.
 

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Re: (Razor1973)

I'll make this real simple, Volvo suspensions bang. The lower profile you go, the louder the "bang" will be. <br>R's "bang" more, Pirelli's bang even more<br>Basically Volvo has a TERRIBLE suspension for a modern car, they haven't the notion of what bumpsteer is and how to tune for it
 

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Discussion Starter · #12 ·
Re: Big wheel/tire impact in large bumps - Why? (geoguy)

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD><i>Quote, originally posted by <b>geoguy</b> »</i></TD></TR><TR><TD CLASS="quote">For example, when coming upon a new layer of asphalt that sits an inch or so above the older pavement that I'm driving on. The front end really feels like it is crashing into a bump.</TD></TR></TABLE><p>That's it! That's the perfect example! Whenever I see one of those coming up, I know it'll be a hard impact, try to lower speed to about 30-40 MPH, but still, <b>BANG</b>! And there's a lot of road construction where I live, where I work and in general all over the city. They call it progress and beautification. I call it "You're not paying for my tires or shocks, goddamnit!"<p><TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD><i>Quote, originally posted by <b>geoguy</b> »</i></TD></TR><TR><TD CLASS="quote">My interpretation is that it is actually the 4C over-reacting, & stiffening up the shock damping too much.</TD></TR></TABLE><p>Can it really react THAT quick??? Based on HOW it feels, my gut tells me this is no stiff shock impact, but a real wheel impact. I hope I'm wrong.
 

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Discussion Starter · #13 ·
Re: (JRL)

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD><i>Quote, originally posted by <b>JRL</b> »</i></TD></TR><TR><TD CLASS="quote">Basically Volvo has a TERRIBLE suspension for a modern car, they haven't the notion of what bumpsteer is and how to tune for it</TD></TR></TABLE><p>I see... One more to add to my list. I can't wait.<p>Now, does it actually <u>damage</u> something or does it just feel like it does?
 

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Re: (Razor1973)

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD><i>Quote, originally posted by <b>Razor1973</b> »</i></TD></TR><TR><TD CLASS="quote"><p>I see... But someone was suggesting the opposite: that I deflate my tires to avoid these impacts.<p>I shall try the 45 psi hot and see.</TD></TR></TABLE><p>I edited my original post...What I wrote was for extremes....<p>Day to day driving with 35-36 psi all around suites me fine for the rough British roads I'm subject to. I have zero complaints with that setting as it hasn't damaged my rims in any manner, and, IMO, provided a solid and smooth ride.<p>Kevin
 

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Re: (Razor1973)

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD><i>Quote, originally posted by <b>Razor1973</b> »</i></TD></TR><TR><TD CLASS="quote"><p>I see... One more to add to my list. I can't wait.<p>Now, does it actually <u>damage</u> something or does it just feel like it does?</TD></TR></TABLE><br>I told you before the best all around pressure for an R (with stock PZeros) is about 34-35 TOPS
 

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Re: (JRL)

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD><i>Quote, originally posted by <b>JRL</b> »</i></TD></TR><TR><TD CLASS="quote">I'll make this real simple, Volvo suspensions bang. The lower profile you go, the louder the "bang" will be. <br>R's "bang" more, Pirelli's bang even more<br>Basically Volvo has a TERRIBLE suspension for a modern car, they haven't the notion of what bumpsteer is and how to tune for it</TD></TR></TABLE><p>Ha ha my main man just saying it as it is
 

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Discussion Starter · #17 ·
Re: (KVB)

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD><i>Quote, originally posted by <b>KVB</b> »</i></TD></TR><TR><TD CLASS="quote">Day to day driving with 35-36 psi all around suites me fine for the rough British roads I'm subject to. I have zero complaints with that setting as it hasn't damaged my rims in any manner, and, IMO, provided a solid and smooth ride.</TD></TR></TABLE><p>Kevin,<p>Is this 35-36 psi with <u>hot</u> tires? Doesn't this make the car feel even "wigglier"?
 

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Discussion Starter · #18 ·
Re: (JRL)

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD><i>Quote, originally posted by <b>JRL</b> »</i></TD></TR><TR><TD CLASS="quote">I told you before the best all around pressure for an R (with stock PZeros) is about 34-35 TOPS</TD></TR></TABLE><p>J-J, that's the thread I was referring to, back from when I first got my R, and my compilation of suggestions from that thread is what made me start inflating my Rossos to 40-41 psi hot. I did actually feel a great improvement in handling and a reduction in body roll and that's my #1 priority. I'll take 5 daily bumps if that makes my car handle better anytime.
 

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Re: (Razor1973)

Install sway bars, reduce tire pressures you'll get the same result, (better).<br>It's a "false" feel you're getting and you're hurting everything from your wheels to your tires and your shocks
 
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