How much bigger can I go on 15in wheels?

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Mar 9, 2012
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I bought a 17 Ford focus it has 195/65r15. Can I go wider and shorter sidewall and keep the 15in? Id like to increase handling if I can. What would be wider and shorter sidewall and still close dimensionally speaking to keep the speedometer close? Maybe a 205/55R15 or something. Seems like there used to be a chart where you could compare sizes vs the radius but I couldn't find it when googling this time around.
 
miata.net has a tire calculator for this.
do it manually ;p

195*2*.65/25.4 + 15 =24.98"
205*2*.6/25.4 +15 =24.69"

215/60r15 which is probably too wide would be 25.16" diameter.

It also helps to know if sizes are available so you arent inventing a size that isnt made :)
 
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tire-size.com and wheel-size.com will do this for you. They will also show you alternates if you put in your car ymm.

FYI, there's a lot of Focus, etc. take-off wheels out there that will mount right up to your car. You could probably get some 16" or 17" possibly even already mounted, for a good price. I put some like-new Michelins and 16" Focus take-offs on an older Volvo for $200 total, after I re-bored the hub-center.
 
Nice to see modern cars that still have real sidewalls :D

The closest wider size seems to be 215/60-15, if you want to keep the 15 inch wheels. As Oro said, you might wish to consider 16-17 inch wheels from the junkyard.

Get Koni Special Active shocks or Bilstein HD.
 
Get serious with a 295/50 :D
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In my experience, tires handle better on wheels nominal for their width. The Tire Rack shows the tire diameter for every tire they sale under specs when viewing a tire.

The perfect tire size for the Focus is 205/55/16. Find some junk yard wheels. VERY popular tire size with the most choices of any small car OEM tire size. Look into the General GMAX AS-05
 
I had a Subaru Legacy wagon years ago with similar if not the the tire size. I think the original steelies were something like 195/70r14. I found a set of 15” alloy take-offs and the standard tire size was 195/65r15. But i plus-oned to 205/60r15 and Loved it.

you can do the math. 195 is the tread width in mm. The second number is the sidewall height. 60 would mean 60 percent on the tread width, so 0.60 x 195. Double that and add it to the wheel size and you have the diameter.

in my case, the 205/60r15 was larger than the original tire, but it was good on that car. I personally find 60 series sidewalls in that size range to be a sweet spot between handling and comfort.
 
16” or 17” rims with some good summer tires will make a big difference. There’s almost no 15” summer tires made any more with the diameter you need.
Sport comp2’s were very good good on my focus, but you need other tires if it gets below freezing in your area in winter.
 
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