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Discussion Starter · #1 ·
Hello, I'm a long time lurker; first time poster. I bought a 2006 V70 yesterday that's equipped with DSTC. It had 18" rims which I considered ugly and had a bad case of curb rash. Also, I live in a Canadian city where deep potholes were invented and I didn't like the fact that there was about 1" of sidewall on these tires. I asked the dealer to replace the 18"s with the pristine 16" rims from another car as part of the deal and he agreed.<p>Now, I am having second thoughts because I'm wondering if the smaller rims will result in the DSTC not operating correctly, or if the speedo will be badly off. Can anyone address these questions?
 

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Re: Switching from 18" rims to 16" considered harmful? (DrXenon)

Rim size does not matter, it is the overall rolling diameter (circumference really) that matters. <p>As long as the sizing has changed appropriately to accomodate, you are fine. <p>I wouldn't worry about DSTC as long as all tires are the same size but if there is a significant difference in the rolling diameter, your speedo will be off. <p>Go to tirerack.com and look at tires in your old size vs. those in your new size. In the sizing chart it should list "revs / mile" for each tire. This will give you an indication of how far things might change. <p>Oh, and 16's are stock size for a V70, I think. Certainly not 18's.
 

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Discussion Starter · #3 ·
I think my V70 has some kind of option package (Sport?) which meant it came with DSTC and better-bolstered seats, as well as 18" wheels.<p>The 18"s, which I assume were 235/40/18, made 818 revs/mi. The 16"s, which I assume are 205/55/R16, make 832 revs/mi.<p>This means the speedo will read about 1.7% faster now, which I don't consider unacceptable.<p>I called the dealer and he said there would be no DSTC programming changes to accommodate the 16" wheels, so I guess the reduced unsprung weight with the 16"s won't matter.
 

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Re: (DrXenon)

On line tire size calculator here: <A HREF="http://www.1010tires.com/tech.asp" TARGET="_blank">http://www.1010tires.com/tech.asp</A>
 

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Re: (DrXenon)

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD><i>Quote, originally posted by <b>DrXenon</b> »</i></TD></TR><TR><TD CLASS="quote">I think my V70 has some kind of option package (Sport?) which meant it came with DSTC and better-bolstered seats, as well as 18" wheels.<p>The 18"s, which I assume were 235/40/18, made 818 revs/mi. The 16"s, which I assume are 205/55/R16, make 832 revs/mi.<p>This means the speedo will read about 1.7% faster now, which I don't consider unacceptable.<p>I called the dealer and he said there would be no DSTC programming changes to accommodate the 16" wheels, so I guess the reduced unsprung weight with the 16"s won't matter.</TD></TR></TABLE><p>Must have been some weird Canadian option. Certainly nothing in the US. Not even the V70R has 18's.
 

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Discussion Starter · #6 ·
Re: (Needsdecaf)

Perhaps I am mistaken about them being 18"s. Here's what they looked like:<p> <IMG SRC="http://dr.xenon1.googlepages.com/IMG_0094.JPG/IMG_0094-full;init:.JPG" BORDER="0">
 

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Re: (DrXenon)

Get the tire size and post it here (I can't see the markings on the tire on my monitor). It should read nnn/nnRnn (e.g. something like 225/55R18). The last number will tell us the rim size.
 

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Discussion Starter · #8 ·
Sorry, I just thought someone might recognize them.<p>I get the car on Saturday; I'll see if I can find another car that has rims that size.
 

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<A HREF="http://www.volvopartspeople.com/SearchProduct.asp?Model=V70&catid=3366984920630563&year=06&productdesc=Cassiopeia+7.5+x+17-inch" TARGET="_blank">http://www.volvopartspeople.co...-inch</A><p>Cassiopeia 7.5 x 17-inch for your '06 Volvo V70:<br>
 

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Discussion Starter · #10 ·
Thanks! The dealer's ad says 18"- just goes to show you can't believe a word they say.<p>The rims I'm getting are Echo 16", which I like better and don't have curb rash. <p>BTW, the dealer replaced the tie rod ends to get the car ready for sale - is this a common repair on these cars?
 

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Re: (DrXenon)

yes, tie rod ends and control arm bushings wear down fast on this chassis (about 50-65,000 kms). They'll last a bit longer with a larger sidewall absorbing some of the shock though (i.e. smaller wheel).
 

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Re: (ss60)

You still need the specs for the tires that are on the car now. Once you get that, go to the 1010 link for their tire size calculator, punch in the size you have now, and then select some 16" tire sizes and find out which ones come closest to the overall diameter of the current tires. The closer their diameter to the current diameter the less likelihood of having speedo and EST and ABS issues.
 

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Discussion Starter · #13 ·
The speedo is about 2 km/h high at 120 km/h according to my GPS, so I'm quite happy.<p>One thing I wasn't happy about is that the car was delivered with 15 psi in one tire. I pumped it up and it has held the pressure for a week. I'll have to take the wheel off this weekend and see if there's a nail or something in it.
 
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