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I have a 2012 VW Passat SEL. Currently I have Han Hankook tires 215/55R17 on them. I am looking to get a full size spare tire and am looking on Craigslist for a cheap alternative. What will be the effect of driving on a 215/47R17.

I found this link explaining what is the 65-45 as the aspect ratio, but what will happen if I drive on a higher or lower aspect ratio number? Can I drive on a higher/lower? If yes, how far high/low can I go with?

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    I think you have a slight misprint in your tire aspect ratio ... it is probably 215/45R17 and not 215/47R17 ... aspect ratios go in 5% increments.
    – Pᴀᴜʟsᴛᴇʀ2 ♦
    Commented Feb 24, 2015 at 21:17

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If the tire were to be used on the rear of the car, the worst that would happen is the ABS light would come on (and possibly the low tire indicator, if so equipped). If it were on the front end (since the Passat is a front wheel drive vehicle), you run the risk of damaging the transaxle (the differential in the transaxle to be specific). When running tires of different sizes on the drive axle, you are forcing the transaxle to behave as if it is constantly going around a corner. This creates a lot of wear on limited slip parts as well as creates a lot of heat. Since it is collocated with the transmission itself, the added heat creates an issue for the transmission portion of the transaxle as well. Heat is the biggest killer of automatic transmissions.

The difference between the two tires you mention is somewhere to this difference:

  • 217/45R17 = 24.6" overall diameter = 77.3" circumference
  • 217/65R17 = 28.0" overall diameter = 87.9" circumference

Please note this is over 10" difference in circumference ... that isn't just a little difference, that's a HUGE difference. If you'd like to play around with how this all figures out, please take a look at this site. Remember, though, this is just a rough estimate as while the numbers look the same, it doesn't mean that one manufacturer's claim to width or aspect ratio is going to be exactly the same as another's.

I have two suggestions for you. First, continue to look on Criagslist. You'll find what you are looking for there. It doesn't sound like you are in a huge hurry to get this done (you don't need it today), so be patient and get what you need. Secondly, see if there is a used tire store around which might have a tire for your vehicle. At least in my area, there are several which charge a set amount for the tire and for mounting/balancing and are very reasonable.

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  • Thanks, you raise very good points! The reason I am looking on Craigslist is because of the price. Town Fair Tires offered me 100 for a new metal rim, and 100 for a new unknown brand tire. I am trying to save on either or both. An alloy rim will be nicer, and I see plenty of those on Craigslist, but none of my make/model. So I am wondering what will happen if I get one from a different make/model with whatever tire, and get the right (user or new) tire from a shop.
    – KingsInnerSoul
    Commented Feb 24, 2015 at 22:35
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    You could also look at purchasing a 15" rim with a higher aspect ratio tyre. That should be considerably cheaper. The best fit would be a 205/70/15 (it's 99.96% the same circumference as the 215/55/17 you have currently).
    – Captain Kenpachi
    Commented Feb 26, 2015 at 14:40
  • @KingsInnerSoul ... I don't blame you about using CL to get a better deal. As Juann was suggesting about a smaller diameter tire, this isn't a bad idea either, as tires for a 15" rim are much cheaper than a 17" tire would be. Instead of doing the math yourself, though, go to someplace like tirerack.com and find the Rotations Per Mile (RPM) for your tire and match it to any tire you are looking at purchasing. If you are within a few RPMs (+/-), you should be golden.
    – Pᴀᴜʟsᴛᴇʀ2 ♦
    Commented Feb 26, 2015 at 15:09
  • They are cheaper. But in that case, what is the effect on driving 15" instead of 17"? MPG? Speed? Wear/tear? Brake time/distance? Control? Turn around diameter (u-turn)?
    – KingsInnerSoul
    Commented Feb 27, 2015 at 22:11
  • @KingsInnerSoul ... As long as it lines up with everything else, it's fine. Think of it as a doughnut on steroids. If you want the spare tire to be like the regular tires, buy another rim/tire just like the regular ones. I'm just providing you alternatives to doing this as you seem adverse to spending large sums of money (which I am as well).
    – Pᴀᴜʟsᴛᴇʀ2 ♦
    Commented Feb 27, 2015 at 22:13
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I used to work at Sears Automotive Center and the answer about aspect ratio was spot on. I had customers coming in all the time wanting to deviate from manufacturer specs, and they really didn't want to hear that improper tires size can damage their cars. When they would get an $1800.00 repair bill for differential damage. ...I would be forced to remind them that they didn't listen when we tried to warn them of what would happen. That's why they are called manufacturers specs.

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