# Tire Ratios

• posted on September 24, 2006, 6:38 pm
My new Civic has 16" (205/55R/16) aluminum wheels so I think i'm going to get some winter rims and tires for it for the comming winter.
I was wondering if I could use 15" wheels & tires instead? If so, what size
tire should I get to keep the right ratio? Anyone know how I can find out? 16 inch low profile winter tires, which would fit right, are just too expensive really and there's no need for such tires for the winter.
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• posted on September 24, 2006, 6:48 pm
ourkid2000 wrote:

You could get a 195/65-15 and your speedometer would be off by only 0.4%.
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• posted on September 25, 2006, 2:12 am

Try this: http://www.eunos.com/tirecalc /
-Dave
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• posted on September 26, 2006, 7:20 am

Yes you can use 15" wheels and tires. This is a -1 fitment (minus one). The goal is to get a wheel/tire combination that gives you the same height and circumference. This is a lot more complicated than it should be because different measurement systems are at work here... The 205 is in millimeters, the 55 is in per cent and the 16 is in inches. What you do is go to a good reputable tire shop and tell them what you want to do and let them do the math for you - or - find the sidewall height expressed as a percentage of the width (205 X .55 in your case), then multiply by two because you have a sidewall at the top and bottom of the tire, then convert that result, which is in millimeters, to inches. Simply multiply by 25.4. Add this result to 16 (the wheel diameter). This answer is the height of your tire. Now you select a tire in 15 inch and match it, as closely as possible, to your stock tire/wheel .... Just as a starting point, I would suggest about a 215/60/15. Hope this helps.
DaveD