Speedo correction?

[Oldnick]

I have put a lower profile tyre on the front of my 98 Valk standard and the speedo is now lower by a calculated 5%, based on tyre diameter ratios. Suddenly I get an extra 10Km out of a tankful.

It's just a nuisance and may even avoid speeding fines  , but I was wondering there is a way to adjust the speedo, either by adjustment or some sort of gearbox. If so, what sort of money am I looking at, to know if it's worth the worry.

I have seen a couple available, but they were specifically for diff ratio changes in specific cars.

Thanks for any advice.

[9Ball]

Your best bet would be a gps or smart phone app to show actual speed.  Based on how the standard and tourer speedo drive is made there isn’t a mechanical fix to this problem that I’m aware of.

The interstate has a different method that might be able to be adjusted using a “speedo healer” that I’ve seen on eBay.

Good luck.  I think a lot of bikes and cars overstate speed to give the impression of higher performance. I know my Subaru WRX STi used the maximum lawful allowable speed error for this very reason.  My Wife’s VTX1300 overstates speed by almost 5 mph at highway speeds using OEM spec tires.

Your case is different in that you altered the dimension of the front tire but the solution remains the same.