160 effect speedo?

[mk2wilson]

Got a question for you guys. I bought my FZ used and the dealership I bought it from put new tires on it. The problem is they put a 160 instead of a 180. Would this effect the speedo? I think it might have, but I'm not sure. I know when I'm running down the interstate, the speedo indicates 75 or so and it just doesn't feel like I'm making that speed. I'm not going to change it until I need a new tire, but it just got me wondering.

 

[jtarkany]

The speedo is notoriously innacurate to begin with, roughly about 10% off after 55 mph on my bike.

The 160 vs. 180 should not have an effect on the speedo as these numbers refer to the tire width, not its diameter.

 

[Senior]

What is the exact spec of the tyre?

It should be 180/55 R17 W (73)

Take the bike back and get them to put the proper size tyre on "free-of-charge". They have sold you "defective goods" and bike does not conform to the manufactures spec.

Depends on the profile part of the tyre spec . . .

This is the proper size. 180/55 R17 W (73)

The profile is 55% of the 180mm width, i.e. the "height" of the tyre from the rim.

Have you got the correct speed rating ? (thats the "W" part of the spec)

Have you got the correct load rating? (thats the "73" part of the spec)

The diameter of the correct tyre should be
431.8mm - 17 inch for the rim
198 mm - 2 x 55% of 180mm (2 x 99mm)
629.8

If you have got a 160/60 R17 H (69) then you'll have:
431.8mm - 17 inch for the rim
192 mm - 2 x 60% of 160mm (2 x 96mm)
623.8

I'd say don't worry about the speedo there's only 6mm difference which is less than 1% . . .

Really, check the speed rating and load rating :thumbup: