XPost: comp.os.linux.misc   
   From: rich@example.invalid   
      
   In comp.os.linux.misc c186282  wrote:   
   > On 12/9/25 06:53, Daniel70 wrote:   
   >> On 9/12/2025 9:09 pm, The Natural Philosopher wrote:   
   >>> On 09/12/2025 08:35, c186282 wrote:   
   >>>> On 12/8/25 17:41, rbowman wrote:   
   >>>>> On Mon, 8 Dec 2025 14:59:12 +0100, Carlos E.R. wrote:   
   >>>>>   
   >>>>>> No, this is intentional calibration of the car speedometer to 5   
   >>>>>> kilometres low. The reason is that if you see a road limit of 100Km/h   
   >>>>>> and you do drive at 100Km/h sharp, there is no possibility of you   
   >>>>>> driving just a bit above the limit and be fined. You could then sue   
   >>>>>> the   
   >>>>>> car maker for having bad instrumentation that caused you to be fined.   
   >>>>>   
   >>>>> That's the reason I've heard for Japanese bike speedometers being   
   >>>>> off. The   
   >>>>> speedometer in the Toyota is accurate when I'm running the 15" tires   
   >>>>> it's   
   >>>>> calibrated for.   
   >>>>   
   >>>>    Yep, tire diameter IS critical.   
   >>>>   
   >>> There is no 'tire diameter'   
   >>>   
   >>> Only circumference.   
   >>   
   >> .... and, as circumference is dependant on diameter/radius ......   
   >   
   >   Exactly.   
   >   
   >   Pi*D = circumference   
      
   Yes, for a perfect circle.   
      
   But a tire under load is no longer a perfect circle, so if you use the   
   loaded "radius" or "diameter" (even though neither really applies to a   
   "non-circular shape") you'll come up short for the "distance around the   
   outside of the tire".   
      
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