i know most all vehicle speedometers are off by a little bit. my '12 SG is 2.5mph fast. would increasing rear tire size help this?

 

Only two and a half? Mine's 5 MPH fast...don't work it to death, dude, just factor it into your game plan...ridin' a Harley ain't about perfection!

 

"...riding' a Harley ain't about perfection!"
I have to disagree with this, but we don't have to be disagreeable. If we were satisfied with stock, we would all ride cookie cutter bikes. My bike is perfect in my eyes, and when it is not any more, I'll fix it till it is. To the OP the only thing really wrong is that if the speed-O-meater is off the odometer will be as well.

 

Yes a taller tire would work providing you can buy one the correct diameter. Of course you could overshoot and end up reading slow.

 

I just adjust for the difference. Mine is 1.8 off so if in a 55 zone I set it right at 60. I have never been stopped. 5 or more will get you stopped but 2 won't
I need all the slack I can get sometimes.

 

Mine is 3 MPH fast when judged against GSP speed. I think they all are and my theory is that it is done purposely by the Motor Company to account for slight vitiation in actual tire sizes from nominal tire sizes. Also some tire brands will grow more than others at high speed.

I don’t worry about it. I like it. It provides a slight fudge factor against speeding tickets.

 

A Power Vision or TTS can adjust it to very near dead on. My 14 limited is right exactly with the GPS. I assume it is correct. 10 and 12 limiteds were 2.5 fast also.

 

Everyone talks about being X mph fast...

At what speed?

It is a percentage, not an exact MPH.

Mine was 4% high, meaning at 25 on the gps, I showed 26, at 50, 52, at 75, 78, and at 100 on the GPS the bike showed 104.

I have a PV2, so I went in and raised the PPU number 4%, now it reads dead nut with an external GPS.

 

My 2012 RGU is just shy of 4mph fast, does affect total miles too but only slightly so I don't care just adjusted to it.

 

read info on the honda vtx I had saying it was 10% fast... kinda a lot. And my gps said that or more

On this RK it shows between 2 and 3 mph fast at 60. I can deal with that. My gps is a handheld type I used for geocaching and hiking in the mts here so not real easy to compare readings. If I go fast enough for that to be an issue, I am usually moving with traffic.