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Discussion Starter · #1 ·
I chose to go with a new Bridgestone 130/70-18 front tire, which should give me a slight error on the speedo. From what I gather, about 10% less speed/distance than actually shown, or an actual 63mph when 70 is showing on the speedo, right?
The original tire on the ACE T is 130/80-18, an unusual size (one of the less desireable features of the T). Only option as far as I know is Dunlop factory replacement.

Does Honda or anyone else make a different speedo sensor that we can install to offset the error? I know for older cars, they make little gear boxes with different ratios that you connect at the tranny where the speedometer cable connects.
Maybe the speedo pickup/sensor will swap from another shadow with stock 18 inch front wheel that was born with a 130/70 front tire?

If not, no big deal and I'll just live with it.

Dan
 

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These speedometers already run about 10% high, so you will need to figure this in as well.
 

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Discussion Starter · #4 · (Edited)
Phantom, that is one high tech website. But their speed healer is for non cable driven speedometers.
Kingshead, thanks. I can see wanting to err on the high side , but 10 percent is ridiculous in my opinion. (What if your check book was 90 percent accurate, or if your boots fit 10 percent too small. Math is math.)
I'll mount the tire next weekend. Then take my gps with me and see how bad it's off.
Dan
 

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I'm not sure where you got 10%. Your original tire circumference is 82.3 inches. Your new tire circumference is 79.1 inches. This is a difference of about 4%, which is what you should see on the speedo. So, 70 on the speedo should represent an actual speed of 67. And every 100 miles you travel would show as 104 miles on the odometer.

Of course, this assumes a couple of things. First, your speedo/odometer is accurate in the first place. And second, that the physical size of your tires actually matches the size printed on the sidewall, which most don't. Each manufacturer allows themselves certain "tolerances" with their tire sizing. Just changing brands can throw your speedo off a couple of MPH, even if you keep the same size.

So, in general, the 4% I figured above should be close. But, I would confirm with a GPS if you are concerned about it.
 

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Discussion Starter · #6 ·
Agreed with you AK Rider. Except with the correct front tire now (about worn out), my actual speed is about 64mph when my speedometer is showing 70. This is verified with gps. So any smaller tire, will make more error.
We'll wait and see how it works...as you said, the actual tire size may not be what's advertised.
Dan
 
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