Downsizing my wheels from 18” to 17”. Where/how to recalibrate speedometer?

ohmygosuness

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Hi all,

I’m downsizing my wheels from 18” (stock) to 17”. Do i need to recalibrate the speedometer? How or where to go about doing this? Any advice will be greatly appreciated.
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REBELXSi

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Pretty sure the common and possibly only way to deal with this issue is simply to deal with it. The difference won't be drastic enough to cause any issues or throw off the speedometer by much.
 
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OP

ohmygosuness

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Pretty sure the common and possibly only way to deal with this issue is simply to deal with it. The difference won't be drastic enough to cause any issues or throw off the speedometer by much.
Found this solution:


This may be the route i’d have to go with. Unless someone has a better solution. I can’t just “deal with it.” It’s going to bother the crap out of me knowing my speedometer is off...
 


REBELXSi

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Found this solution:


This may be the route i’d have to go with. Unless someone has a better solution. I can’t just “deal with it.” It’s going to bother the crap out of me knowing my speedometer is off...
Nice, I had no idea such a thing existed.

Any idea how much your new tires would have offset the speedo? I'm assuming his case was further off since he went and swapped out his final drive.
 

silverrascal

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You could go with 215/50/17 which is the stock tire size of non-Si Civics. Prior, I had upgraded from stock 17s to Si 18s which virtually are the same circumference and thus little speed differences. You could also find a tire calculator online and most will do the conversion for you.
 

VarmintCong

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Thanks. I guess my question was do i take it to a shop or dealer to do this? Or can i do this by myself?
First check how much your tire diameter changed. Then use a GPS or nav app and see your real speed. It's dead on in my Civic w/ aftermarket tires (don't remember if it was off when stock).
 

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wheel size doesn't matter for speedo, it's overall diameter of your tires. Just get the right tire size to get you the same overall diameter and you won't need to mess with anything.
 


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I went with a wider and lower profile tire. Off maybe 2mph. Not enough for me to really care.

Honda Civic 10th gen Downsizing my wheels from 18” to 17”. Where/how to recalibrate speedometer? IMG_20190907_104202_833
 

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OP, like another poster mentioned, you can go down an inch in wheel size, but simply use a higher profile than stock tire to keep your speedo accurate. In this case you could use the 215/50-17 size like on my non-Si.

But, I have an even better solution for your Si:

Use the 17" stock European Civic tire size... 235/45-17. It's much meatier yet will still keep your speedo numbers virtually identical to stock. The great thing with this is you'll have the same width as the stock Si tire but will get a cushier ride due to the 45 profile.
 
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VarmintCong

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OP, like another poster mentioned, you can go down an inch in wheel size, but simply use a higher profile than stock tire to keep your speedo accurate. In this case you could use the 215/50-17 size like on my non-Si.

But, I have an even better solution for your Si:

Use the 17" stock European Civic tire size... 235/45-17. It's much meatier yet will still keep your speedo numbers virtually identical to stock. The great thing with this is you'll have the same width as the stock Si tire but will get a cushier ride due to the 45 profile.
That's the tire I have on my Sport hatch. Weren't many choices of summer tires so I went with Pilot A/S 3+.
 
OP
OP

ohmygosuness

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I really appreciate everyone for the advice on getting the right tire size. Unfortunately when i ordered the wheels, i also got me some 225/50-17 tires attached to them. I guess i should have waited and do some more research.

If recalibrating doesn't work, i’ll definitely go with the 235/45-17.
 

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