I have an AP1 w/ AP2 wheels and oem tires. My speedo is consistantly 4 mph off. I've done some pretty basic testing-state patrol radar, county radar, speed radar on the side of the road. I don't have a GPS to test with. But every time I do a pass, the car reads 4 mph faster. Could it be the AP2 wheels/tires?...I figured they would be the same ratio. I'm thinking of going 18 and wanted to address this issue befor hand.

 

yellow box it or have dealer retune the calibration.

http://www.ricks2k.com/products/yellowbox.php

 

yes. I knew about the yellow box.

 

When you say "the car reads 4 mph faster" do you mean your speedometer reads 4 mph faster than the radar? If that's the case, I don't think it's a problem. My last two cars, including the S, would show ~3 mph more on the speedometer than on my GPS, radar signs, etc. I've heard of many other people noticing the same thing. I've always wondered why, but I don't really care unless my speedo is reading too low.

But, if you're saying your speedo reads 4 mph too low, then you have a problem worth investigating. Could be the AP2 wheels, but someone else here will have to confirm.

 

Honda's cars are designed to be off by a tad. There was a law suit about it. www.odosettlementinfo.com

I would suggest a yellow jacket from HTG or as mentioned above, the yellow box for Rick's.

 

yeah-for example car reads 84 and radars read 80. I agree...not really a problem-probably a blessing in diguise. I didn't think it would have been the AP2 wheels but since you guys mentioned the variance from the factory-it makes more sense. Looking into yellow box. But prolly will leave it alone.

 

You are saying it's a constant 4mph? As in, it reads 4mph when the car is idling?

 

That's exactly how I look at it. Since I usually do 5-10 mph over the limit, I may have been saved from a ticket once or twice...who knows?

I really don't think you need to throw down the money for a yellow jacket/box. Do you really need to know the exact speed? You already know you're moving 4 mph slower than the speedometer indicates, so you can always do the math in your head if you want.

 

4mph error is MASSIVE, or nothing, depending on what speed. If at ACTUAL 25mph your car reads 29mph, thats a MASSIVE error. There is no way OEM wheels/tires are to blame.

Now, as speed builds, the error will rise exponentially....if at 25, you read 29, and at 100 you read 104, there is something wrong with the radars. If it was a speedo error, you would read 25/29 and 100/116.

Does the error rise as the speed rises?

 

^^^ you're probably on to something. I assume the speedometer...wait. Have I been calling the effin speedometer an odometer this whole time??? I don't know what I was thinking...sorry for being such an idiot. I'll go back and edit my posts so no one gets more confused than I. thanks for not flaming me everyone

Anyway, NFRs2000NYC, you have a good point. I assume the speedometer doesn't read -4mph at idle. That would mean the 4 mph offset wouldn't be constant. At higher speeds, the error should get drastically worse