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I am not very versed in tire sizing. Can someone there tell me the difference beween a 225/45-18 and a 235/40-18 and if they would be interchangeable on my s60 r.<br>Thanks for the help.<br>
 

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Re: Tire size (Reno R)

Difference is 10... <IMG NAME="icon" SRC="http://www.vwvortex.com/vwbb/biggrin.gif" BORDER="0"> <p>225 is a tad smaller in diameter and officially not the correct tire size for the R.<br>Also the load rating can be a problem with the smaller size depending on brand.<p>For a winter tire it should be OK to use, Speedo will be slightly off.<br>
 

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Re: Tire size (Johann)

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD><i>Quote, originally posted by <b>Johann</b> »</i></TD></TR><TR><TD CLASS="quote">Difference is 10... <IMG NAME="icon" SRC="http://www.vwvortex.com/vwbb/biggrin.gif" BORDER="0"> <p>225 is a tad smaller in diameter and officially not the correct tire size for the R.<br>Also the load rating can be a problem with the smaller size depending on brand.<p>For a winter tire it should be OK to use, Speedo will be slightly off.<br></TD></TR></TABLE><p>ehh... 225 is a narrower tire, not a smaller diameter. In short, this is how it works:<br>example: 235/40ZR18<p>235 is the section width. The 225 indicates this tire is 225 millimeters across from the widest point of its outer sidewall to the widest point of its inner sidewall when mounted and measured on a specified width wheel.<p>40 The measurement is the tire's section height, and also referred to as the tire's series, profile or aspect ratio. The 40 indicates that this tire size's sidewall height (from rim to tread) is 40% of its section width.<p>Z- a Z rated tire (this one's not always present here, but you'll find it somewhere) which is high speeds. You should go with a Z rated tire for the R. This is the speed rating.<p>R- identifies that the tire has a Radial construction in which the tire's body plies "radiate" out from the imaginary center of the wheel. Any tire you buy for the R will be a radial<p>18- The 18 indicates the tire and wheel diameter designed to be matched together. Tires that have a rim diameter expressed in inches. (18 inch wheel = 18 inch tire)<p>there is also a service description after the size in most cases, but not always on Z rated tires<p>ex. 89S - <p>The first two digits (89S) represent the tire's load index and are followed by a single letter (89S) identifying the tire's speed rating... but this really about tire size, so I'll shut up.<p>Hope that helps. (sometimes I'm the only one who can understand the things I say)<p>
 

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Re: Tire size (Reno R)

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD><i>Quote, originally posted by <b>Reno R</b> »</i></TD></TR><TR><TD CLASS="quote">I am not very versed in tire sizing. Can someone there tell me the difference beween a 225/45-18 and a 235/40-18 and if they would be interchangeable on my s60 r.<br>Thanks for the help.<br></TD></TR></TABLE><p><br>The total diameter of the first wheel is 18 + 2*(3.98) = 25.96"<br>The total diameter of the second wheel is 18 + 2*(3.7) = 25.4"<p>Percentage reduction in diameter is 2.1% Your speedo will be off by 2.1% if you use the 225 / 45 tire (will read slower).<p>It's narrower, so you shouldn't have any problems with rubbing (I'm assuming that the 235/40 is the stock 18" size?)<p>Go to tire rack.com They have a specs page for their tires which lists revolutions per mile. Look at the revs / mile for your original tire and the revs per mile for the tire you are looking at, it will give you an idea of how much speedo error to expect without all the math. <p>Edited so as not to repeat all the stuff Josbro said - just keeping the math.
 

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Re: Tire size (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"><br>The total diameter of the first wheel is 18 + 2*(3.98) = 25.96"<br>The total diameter of the second wheel is 18 + 2*(3.7) = 25.4"<br></TD></TR></TABLE><p>ahh... I see. Johann was referring to the 225 TIRE, not the number 225... got it!<p>I think the biggest negative with a 225 would be MINIMAL rim protection from curbs, as the wheel will be sticking out further than any part of the tire (think of the Acura TL wheel). Also, this looks just a little goofy.<br>
 

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Re: Tire size (JOSBRO)

Actually, the 225 / 45 has a larger diameter than the 235 / 40<p>My math is a little goofy this am (told you that the 225 is a NOMINAL section).<p>According to tire rack.<p>235 / 40 has a diameter of 25.2", with revs / mile being 801.<br>225 / 45 has a diameter of 25.7", with revs / mile being 805. <p>So you have 4 revs / mile difference. 4/800 is 0.5%.<p>Pays to read the specs. <IMG NAME="icon" SRC="http://www.vwvortex.com/vwbb/biggrin.gif" BORDER="0"> <p>
 

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Re: Tire size (needsdecaf)

Excellent site for determining impact (as respects revs/mile, diameter, speedo error, etc...) of switiching from size tire to another:<p><A HREF="http://www.miata.net/garage/tirecalcold.html" TARGET="_blank">http://www.miata.net/garage/tirecalcold.html</A><p>Regards,<p>Derek<br>
 

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Re: Tire size (bb vign)

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD><i>Quote, originally posted by <b>bb vign</b> »</i></TD></TR><TR><TD CLASS="quote">Excellent site for determining impact (as respects revs/mile, diameter, speedo error, etc...) of switiching from size tire to another:<p><A HREF="http://www.miata.net/garage/tirecalcold.html" TARGET="_blank">http://www.miata.net/garage/tirecalcold.html</A><p>Regards,<p>Derek<br></TD></TR></TABLE><p>Interesting that the calculator on that site agrees with my calcs, but not the ones posted on tire rack. It also showed a 2% speedo error. <p>As I said above, the dimensions are nominal, the actual dimensions may not be 225, 235 etc. I would trust the manufacturer specs for outside diameter and revs / mile more than that site. Having said that, it's a pretty nifty little calculator which makes it a lot easier than the math I did above. <IMG NAME="icon" SRC="http://********************/smile/emthup.gif" BORDER="0">
 

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On both my R's - i went to 225/45 R18's - which filled the wheel well a little better without spacers. A little taller but a little narrower than the stock size - in layman's terms.<p>Now - on my 3rd set of tires for my 06 R - I'm at 245/40 ZR 18's with 10mm spacers front, 15mm spacers back. No rubbing and it looks and rides great. <p>AND - it's within tolerances according to my dealer.<p>Just my .02.
 

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Re: (parkstephen)

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD><i>Quote, originally posted by <b>parkstephen</b> »</i></TD></TR><TR><TD CLASS="quote">On both my R's - i went to 225/45 R18's - which filled the wheel well a little better without spacers. A little taller but a little narrower than the stock size - in layman's terms.<p>Now - on my 3rd set of tires for my 06 R - I'm at 245/40 ZR 18's with 10mm spacers front, 15mm spacers back. No rubbing and it looks and rides great. <p>AND - it's within tolerances according to my dealer.<p>Just my .02.</TD></TR></TABLE><p>I agree. I put 245's on with the new wheels and I like them a lot more. It is more comfortable and fills in the wheel well a lot better.
 
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