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There's been some discussion regarding the effect tire size has on speedometer accuracy. Here are my recent observations.
I have a instrument cluster which I believe is from the Philippines that goes up to to 180km/hr with no imperial markings at all.
With my 155-80/13 winter tires the speedo is bang on accurate confirmed both by GPS and roadside speedometer test sections. With my 185-60/13 summer tires the speedo reads almost 5% fast (100kph indicated vs. 95kph actual).
When compared to our stock size tires, 145-80/12, my speedo should run about 8% slow with the winter tires (100 indicated vs. 108kph actual) and about 3% slow with the summers (100kph indicated vs. 103kph actual). I used the tire size comparison tool here to figure that out.
Just wondering if the internal gearing for the speedos from markets other than North America have different ratios?
I have a instrument cluster which I believe is from the Philippines that goes up to to 180km/hr with no imperial markings at all.
With my 155-80/13 winter tires the speedo is bang on accurate confirmed both by GPS and roadside speedometer test sections. With my 185-60/13 summer tires the speedo reads almost 5% fast (100kph indicated vs. 95kph actual).
When compared to our stock size tires, 145-80/12, my speedo should run about 8% slow with the winter tires (100 indicated vs. 108kph actual) and about 3% slow with the summers (100kph indicated vs. 103kph actual). I used the tire size comparison tool here to figure that out.
Just wondering if the internal gearing for the speedos from markets other than North America have different ratios?
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