How much will a tire size change affect my speedometer? - Mazda3 Forums : The #1 Mazda 3 Forum
 
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post #1 of 7 (permalink) Old 05-11-2012, 08:36 PM Thread Starter
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How much will a tire size change affect my speedometer?

I was just at a tire shop looking at new tires for my '10 Mazda3. The factory tire size is P205/50R17. The guy at the tire shop told me that I could easily put on P215/50R17 tires on the car (which I didn't really know was possible). How much would this affect my speedo and odometer, and is this generally a good or bad idea? I want to keep the stock wheels on the car, but the increased tire size has a much better selection to choose from as far as replacements go.
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post #2 of 7 (permalink) Old 05-11-2012, 08:57 PM
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Re: How much will a tire size change affect my speedometer?

[quote author=Guitar Salad link=topic=209961.msg4228384#msg4228384 date=1336782969]
I was just at a tire shop looking at new tires for my '10 Mazda3. The factory tire size is P205/50R17. The guy at the tire shop told me that I could easily put on P215/50R17 tires on the car (which I didn't really know was possible). How much would this affect my speedo and odometer, and is this generally a good or bad idea? I want to keep the stock wheels on the car, but the increased tire size has a much better selection to choose from as far as replacements go.
[/quote]

you have some options without changing the diameter of the tire greatly or affecting the speedo too much.
Rather than tell you...here is a great calculator that will tell you the difference for various tire sizes.
lots of people go wider....
http://www.1010tires.com/tiresizecalculator.asp

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post #3 of 7 (permalink) Old 05-11-2012, 08:59 PM
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Re: How much will a tire size change affect my speedometer?

They would read 1.6% higher speed
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post #4 of 7 (permalink) Old 05-12-2012, 01:07 AM
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Re: How much will a tire size change affect my speedometer?

[quote author=adumbrille link=topic=209961.msg4228392#msg4228392 date=1336784393]
They would read 1.6% higher speed
[/quote]

negative ghostrider
it will be bigger so....actual speed is higher, speedo reads lower

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post #5 of 7 (permalink) Old 05-12-2012, 11:37 AM
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Re: How much will a tire size change affect my speedometer?

oops. That's what I meant. 1.6% higher speed. Hence the speed would read slightly lower
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post #6 of 7 (permalink) Old 05-12-2012, 11:58 AM
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Re: How much will a tire size change affect my speedometer?

[quote author=adumbrille link=topic=209961.msg4228485#msg4228485 date=1336837062]
oops. That's what I meant. 1.6% higher speed. Hence the speed would read slightly lower
[/quote]

yup. speedo would read 59 when he is going 60mph.

2006 Whitewater Pearl Mazda 3 S GT Hatch: Garage Vary Valiant Lip, Grill and Eyelids : Custom JL/Alpine Audio : MazdaSpeed Accessory Springs and Swaybars : JDM MazdaSpeed Strut Bar : Koni Yellows : 5Zigen Pro Racer zr520 : Continental ExtremeContact DW : Buddy Club Condenser : XE Pedals : Black Rays Lugs : HP Tint : Stubby :
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post #7 of 7 (permalink) Old 05-12-2012, 12:24 PM
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Re: How much will a tire size change affect my speedometer?

[quote author=Guitar Salad link=topic=209961.msg4228384#msg4228384 date=1336782969]
I was just at a tire shop looking at new tires for my '10 Mazda3. The factory tire size is P205/50R17. The guy at the tire shop told me that I could easily put on P215/50R17 tires on the car (which I didn't really know was possible). How much would this affect my speedo and odometer, and is this generally a good or bad idea? I want to keep the stock wheels on the car, but the increased tire size has a much better selection to choose from as far as replacements go.
[/quote]


Once my 205/50R17's are worn out, I plan to install 215/50R17's. Like your tire guy said, much better tire selection plus the 205's look totally wimpy on our Mazda. The 215's would be slightly wider & just slightly taller, improving handling & performance.

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