I just added an 18" rear wheel/tire, and when I stood it side by side with the 16, it looks to be about 2 inches taller.

I guess I'll have to use a GPS to measure speed and then know where the speedo is at.

~Joe

 

if it looks 2 inches taller when side by side, then you didn't use a low profile tire which would put the overall diameter in roughly the same place.

 

16" rear wheel & tire measures 25.33", 18" measures 26.18", or right around a 7/8" difference. Yes, this will throw your speedometer off, yes, it's an easy fix with a TTS.

 

Tire is a D407~180/55B18 on my H/D Anarchy wheel

Stocker is a 180/65B16

Maybe some if it is that the stockers is at least half worn out, and thus has a bit of a flat spot in the center.

~Joe

 

Well, I use a PC-V with an Autotuner.

I'll just have to check the speed with a GPS, figure out the variance, and mentally make allowances for it when I ride.

~Joe

 

using the tire calculator that i refernced in an above post, the 18 inch tire should have a diameter of 25.8 inches, while the 16 inch tire should have a 25.2 inch diameter.

so new tire to new tire, your 18 inch should be slightly more than 1/2 inch taller

 

I was looking into that wheel upgrade. I wondered about the same thing. I had to install a speedohealer on my Hayabusa just to get an accurate speed reading with everything stock. I will plan on the low profile rear tire combo.

 

I went with a 18 inch rear,and according to the police radar on the side of the road it's off 2mph.

 

which way? is the speedo reading faster or slower than you are actually moving? if faster, i would ignore it and act as if it is accurate. we can all use a little 'cushion' from time to time.....

 

exactly.