I have stock tires on my 09 classic, when I'm driving 100 km per hour according to the GPS my speedometer shows 111, basically shows 9 to 10% too fast. What's the largest diameter tire I could put on here to compensate for that?

 

What does the door jam sticker say is the correct size?

Not entirely sure though I have yet to inform my daughter her speedo is 6mph fast at 80mph. Seriously though there are tire size calcs all over the internet.

 

What is your current tire size?

Also, https://tiresize.com/calculator/

 

I wouldn’t go much over 25”.
that would be 185/70/15,
195/60/16 or 205/50/17.

if lowered or if heavily laden, even
these choices can rub some.

 

Don't remember details, but it is possible to adjust the deviation electronically (at least on my 2010 LCI). Either from within the service reset menu or the hidden menu.

 

Yes, you can callibrate it from the secret menu.

I can't be bothered spending the time to find all the information, but I remember in my tinkering in secret menus on the R56 that it was there

 

The “secret” menu option is not a calibration, it will instead display actual sensor value for road speed instead of the adjusted “corrected” road speed.

To the OP: 100km/hr to 111km/hr is a big jump. Are you sure the tire you have are OEM size?

 

https://www.northamericanmotoring.co...rrections.html

 

I have 185 65 15 tires