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Discussion Starter · #1 ·
So, I got new tires a few weeks back, and I've been chalking them to get them at the right pressure. 32 psi seems to be the sweet spot for the front, but I've got the rears at 29 psi (which is the "optional" pressure listed in the gas filler cap door), but that's still too high. (Mind you, this is all with just me driving and nothing in the trunk.)<p>Anyway, the question is: would it be dangerous in any way to run the rear tires at any lower of a pressure? Should I just leave 'em be (and deal with the terrible handling) and make sure I rotate them religiously? <IMG NAME="icon" SRC="http://www.vwvortex.com/vwbb/tongue.gif" BORDER="0">
 

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Why do you need the rear tires so LOW? They should be at least 34-36. It's fine to run them in the high 20's, but you're handling and gas millage will suffer, but your straight line traction will improve(on front tires).
 

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Most people pump the heck out of street tires to help with not having sidewall flex.
 

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Discussion Starter · #4 ·
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD><i>Quote, originally posted by <b>cmurphy2266</b> »</i></TD></TR><TR><TD CLASS="quote">Why do you need the rear tires so LOW? They should be at least 34-36. It's fine to run them in the high 20's, but you're handling and gas millage will suffer, but your straight line traction will improve(on front tires). </TD></TR></TABLE><br>I'm just going based on chalking the tread and trying to get a reasonable contact width...<p><TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD><i>Quote, originally posted by <b>JoshV70_</b> »</i></TD></TR><TR><TD CLASS="quote">Most people pump the heck out of street tires to help with not having sidewall flex.</TD></TR></TABLE><br>To help with <i>not having</i>? Or to help <i>reduce</i>?
 

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Re: Tire Pressure Question: Can I go lower than 29 psi? (StarmanDXE)

Just make them 32 all around. If your rears are having contact problems it's probably an alignment issue.<p>The effect of lower pressure on the back is lower traction. The car will start to oversteer (back breaks loose on truns, especially in the rain) if you set em too low.
 

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Help reduce. Had a brain fart. Street is not a race track, so just put them at 32-35 and forget about it.
 

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Discussion Starter · #8 ·
Re: Tire Pressure Question: Can I go lower than 29 psi? (ss60)

Well, here are some pictures:<p>Rear passenger's (29 psi):<p><A HREF="http://lh6.ggpht.com/_eE0yNOema1A/SdV2LSG7PVI/AAAAAAAAApQ/Hv0JWaiXMHQ/s800/IMG_1464.JPG" TARGET="_blank"><IMG SRC="http://lh6.ggpht.co/_eE0yNOema1A/SdV2LSG7PVI/AAAAAAAAApQ/Hv0JWaiXMHQ/s200/IMG_1464.JP" BORDER="0"></A><p><br>Rear driver's (29 psi):<p><A HREF="http://lh6.ggpht.com/_eE0yNOema1A/SdV3RSn7rcI/AAAAAAAAAps/cC1dwLiBsZg/s800/IMG_1469.JPG" TARGET="_blank"><IMG SRC="http://lh6.ggpht.co/_eE0yNOema1A/SdV3RSn7rcI/AAAAAAAAAps/cC1dwLiBsZg/s200/IMG_1469.JP" BORDER="0"></A><p><br>Front passenger's (32 psi):<p><A HREF="http://lh6.ggpht.com/_eE0yNOema1A/SdV2MTVDm3I/AAAAAAAAApY/tq3dLClkVWo/s800/IMG_1467.JPG" TARGET="_blank"><IMG SRC="http://lh6.ggpht.com/_eE0yNOema1A/SdV2MTVDm3I/AAAAAAAAApY/tq3dLClkVWo/s200/IMG_1467.JPG" BORDER="0"></A><p><br>Maybe you're right: maybe I do just need an alignment... If it's not the tire pressure, then there's definitely <i>something</i> going on... <IMG NAME="icon" SRC="http://www.vwvortex.com/vwbb/rolleyes.gif" BORDER="0"> <p><b>Edit:</b> Removed rear-tire pictures as they are rather irrelevant. (Chalk lines hadn't worn enough/correctly.)<BR><BR>
<i>Modified by StarmanDXE at 10:08 AM 4-5-2009</i>
 

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Also remember that the contis have a very wide shoulder... put them at 32 and get your alignment checked
 

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Discussion Starter · #10 ·
Re: (Bender)

Well, it rained yesterday, so I re-chalked my tires today and drove around a good bit. They're still at 32/29, and that seems to be right-on-the-money. Guess I'll leave it at that! (And up it to 34/33 [or so] whenever I go home on the highway and have crap in the trunk and other people in the car.)
 

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Re: (JoshV70_)

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD><i>Quote, originally posted by <b>JoshV70_</b> »</i></TD></TR><TR><TD CLASS="quote">Most people pump the heck out of street tires to help with not having sidewall flex.</TD></TR></TABLE><p>Exactly ... head out to a track and most knowledgeable people will tell you to pump them up 40 or 42psi for the day.
 

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Discussion Starter · #12 ·
Heh. Well, I generally drive my street tires like I'm <i>on the street</i> (as opposed to on a track... <IMG NAME="icon" SRC="http://www.vwvortex.com/vwbb/rolleyes.gif" BORDER="0"> <IMG NAME="icon" SRC="http://www.vwvortex.com/vwbb/tongue.gif" BORDER="0">) I'm shooting for proper inflation so that I get the best wear from my tires.
 

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Re: Tire Pressure Question: Can I go lower than 29 psi? (StarmanDXE)

Those are about the worst looking Contis I've ever seen! <IMG NAME="icon" SRC="http://www.vwvortex.com/vwbb/eek.gif" BORDER="0"> <br>I'm always the one who says run lower pressures but NOT with Contis.<br>They have a soft sidewall so they need to be run at a higher pressure.<br>On an S60T5 I would run 33-34 front, 32-33 rear minimum. Remember I run these tires on both my V70R's<br>The ride should not be rough, if it is you have other issues
 

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Discussion Starter · #14 ·
Re: Tire Pressure Question: Can I go lower than 29 psi? (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">Those are about the worst looking Contis I've ever seen! <IMG NAME="icon" SRC="http://www.vwvortex.com/vwbb/eek.gif" BORDER="0"></TD></TR></TABLE><br>Hmm... In what sense?<p><TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD><i>Quote »</i></TD></TR><TR><TD CLASS="quote">I'm always the one who says run lower pressures but NOT with Contis.<br>They have a soft sidewall so they need to be run at a higher pressure.<br>On an S60T5 I would run 33-34 front, 32-33 rear minimum. Remember I run these tires on both my V70R's<br>The ride should not be rough, if it is you have other issues</TD></TR></TABLE><br>Ride isn't rough. I'm just trying to get them to wear correctly. What should the chalk line look like? As is, all 4 are coming out like the front tire pictured above.<p>Thanks for the input. <IMG NAME="icon" SRC="http://********************/smile/emthup.gif" BORDER="0">
 

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Re: Tire Pressure Question: Can I go lower than 29 psi? (StarmanDXE)

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD><i>Quote, originally posted by <b>StarmanDXE</b> »</i></TD></TR><TR><TD CLASS="quote"><p><br>Ride isn't rough. I'm just trying to get them to wear correctly. What should the chalk line look like? </TD></TR></TABLE><p>Try an alignment.<br>Are all you suspension and steering parts in order.<br>I had a set on an S60 AWD for 33K miles and they wore perfectly
 

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Discussion Starter · #16 ·
Re: Tire Pressure Question: Can I go lower than 29 psi? (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">Try an alignment.<br><b>Are all you suspension and steering parts in order.</b><br>I had a set on an S60 AWD for 33K miles and they wore perfectly</TD></TR></TABLE><p>I doubt it! <IMG NAME="icon" SRC="http://www.vwvortex.com/vwbb/rolleyes.gif" BORDER="0"> <IMG NAME="icon" SRC="http://www.vwvortex.com/vwbb/frown.gif" BORDER="0"> Getting that all fixed up will certainly be in order come summer when I have the spending money. I'll get an alignment done then, too.<p>So, what does "wearing perfectly" <i>look</i> like? How should the chalk lines look? Should it not wear all the way to the outside of the tread, but not onto the sidewall? That's what it's doing and, from what I understand, that's the correct way to do it... <IMG NAME="icon" SRC="http://www.vwvortex.com/vwbb/confused.gif" BORDER="0">
 

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Re: Tire Pressure Question: Can I go lower than 29 psi? (StarmanDXE)

Ryan,<p>From one State Penn'er to another <IMG NAME="icon" SRC="http://www.vwvortex.com/vwbb/wink.gif" BORDER="0">, if wear is what you are going after you want more pressure. <p>Heat stress is a major, maybe the primary, cause for for tire casing wear. It also effects tire wear. <p>The softer the tire, the more deformation you'll have and the greater the heat that will be generated--as well as increased energy expended to rotate the tires, i.e. lower mpg's . Your tire pressure will vary more as a result. It will squirm more at the lower temperature; you will get better cornering--at all speeds--at higher pressures. <p>Most tires these days are designed to run at higher pressures, I believe that the manufacturers spec lower pressures only to soften the ride.<p>I run my tires (all touring/street driving) at 40psi, I get even wear and long life. Yes, the ride is a little harder, but I don't mind--most around here would probably run a little lower for this reason. I also get the added benefit that I don't have to check my pressure as frequently; if the temps drop (say in the spring/fall when they are bouncing around a lot), I have a lot of headroom before they are seriously underinflated and a problem<p>About the only time you want to run low pressures is at the beach. As far as the hazazrds of underinflation, there are only two words you need to know: Firestone & SUV. <IMG NAME="icon" SRC="http://www.vwvortex.com/vwbb/eek.gif" BORDER="0">
 

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Discussion Starter · #19 ·
Re: Tire Pressure Question: Can I go lower than 29 psi? (MrTippy)

Thanks for the reply. Some interesting points of discussion.<p>I'm not really going for <i>extended</i> wear as much as I'm going for <i>even</i> wear. Most of the time, I just drive around town on short little trips. When I do go home (on the highway), I will definitely pump the tires up a bit more (both for better fuel economy and also due to the added weight in the car). While most people want to drive their car and be a passive bystander when it comes to maintenance, I would rather be an active contributor to <i>everything</i> having to do with my car because, the more I understand it, the more comfortable I am with driving it <IMG NAME="icon" SRC="http://www.vwvortex.com/vwbb/smile.gif" BORDER="0"><p>Yes yes, I do understand the problems caused by under inflation. But that's not to say that <i>over</i> inflation can't cause problems too. If you over inflate, the contact patch shrinks and you sacrifice handling and stopping distance. Also, you get balding in the center of your tire which causes worse traction in a shorter number of miles.<p>So anyway, I suppose the real question here is: just how far down the shoulder do I want the tire to be in contact with the ground?<p><br><TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD><i>Quote, originally posted by <b>Young Burnsy</b> »</i></TD></TR><TR><TD CLASS="quote">Why didn't you get an alignment done before you put the tires on?</TD></TR></TABLE><br>Sadly, I have not found where they grow those money trees yet... <IMG NAME="icon" SRC="http://www.vwvortex.com/vwbb/frown.gif" BORDER="0"> But, when I have the money this summer, I'll probably get some new suspension bits put in, and that would be a better time to get an alignment. <IMG NAME="icon" SRC="http://********************/smile/emthup.gif" BORDER="0">
 

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Re: Tire Pressure Question: Can I go lower than 29 psi? (StarmanDXE)

I have experimented with everything from 30-40psi. Anything over 35 starts to get choppy, and anything under 32 starts to affect handling. Of course this is subjective, but that might help you out.
 
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