Wheel sizes and tyres changing speedo

We all (should) know that changing wheel / tyre sizes to that of non original manufacturer wheels can throw out the speedo accuracy / reading.

Question is, what can be done to get it recalibrated so its accurate? If there is such a way?

Depending if it’s cable driven speedo or digital interfaced.

If digital you can buy a kit at jaycar that allows you to adjust and correct the speedo so it is correct.

If cable I think you can get it recalibrated but not sure how maybe @Mr_Gormsby could comment there…

Cable speedo for the Applause.

Any chance you know about changing diff ratios to correct the speedo reading?

How far out are you talking? With different profile tyres and rim sizes it won’t be out that much. There’s a few calculators online that will work it out for you.

For cable it depends on the speedo drive and driven gears for example the cuore with it’s 13 wheel tyre combo has a 21/5 driven/drive whereas the sirion with it’s 14 inch wheel and tyre combo uses 16/4 driven /drive. Not that easy to change as the as the nylon drive gear on these sit’s between 3rd and 4th gears on the output shaft.


Using willtheyfit.com Screenshot_20170927-175908


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I’ve not played with these on Daihatsus, but other cars I’ve do fixes on it was just a matter of changing those nylon gears as 601to602 has mentioned. Pull the drive unit out and if it is eccentric you should be able to calc how many teeth you need. I’d draw one up in Sketchup, save as a .stl and print it out at work using just pla. When you have it set right pay to have it printed in nylon. Or do what I’ve done and install a motorbike dash which uses a magnetic pick up off a spot on a drive shaft output - really easy to calibrate.