How far off is my speedometer now?
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How far off is my speedometer now?
I replaced the stock tires/rims with 17" wheels and taller than stock all weather (Blizzaks). While I was doing the switch, I laid a blizzak+wheel over a stock+wheel, the blizzak combo is about 1/4" bigger in all directions. In other words, when you stood them up next to each other on a level surface, the top of the blizzak combo is about 5/8" taller at the top.
Is my speedo reading faster, slower, or so close to the same that it doesn't matter? And what about the odometer?
Question # 2, since this combination is much smoother and quieter, and the tread on the original tires is getting thin, I'm thinking of leaving these in place all summer in '06. Bad idea? Pros and Cons?
Is my speedo reading faster, slower, or so close to the same that it doesn't matter? And what about the odometer?
Question # 2, since this combination is much smoother and quieter, and the tread on the original tires is getting thin, I'm thinking of leaving these in place all summer in '06. Bad idea? Pros and Cons?
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Bigger wheels = more distance traveled per rotation, so your spedo will be slightly under the real speed. Same with the odometer. You could work it out, you know the diameter of each wheel, so you can work out the circumference, and then find out the percentage difference.
If the distance traveled / circumference was 10% more then the spedo would be 10% slower, well, that's what I think. Am I right?
If the distance traveled / circumference was 10% more then the spedo would be 10% slower, well, that's what I think. Am I right?
Last edited by Critters; 11-01-2005 at 08:19 AM.
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http://www.miata.net/garage/tirecalc.html
Enter your old tire size, new tire size and it will tell you the circumference differences as well as the impact on your speedo
Enter your old tire size, new tire size and it will tell you the circumference differences as well as the impact on your speedo
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Originally Posted by willhave8
http://www.miata.net/garage/tirecalc.html
Enter your old tire size, new tire size and it will tell you the circumference differences as well as the impact on your speedo
Enter your old tire size, new tire size and it will tell you the circumference differences as well as the impact on your speedo
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There is a wealth of great info here === http://forum.miata.net/vb/forumdisplay.php?f=12
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Great help! Wow. Thanks a lot. I'm off by about 1.2% - speedo reading too slow, but that's only about 1 MPH at 70, so I doubt it'll land me in jail.
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