XPost: comp.os.linux.misc   
   From: robin_listas@es.invalid   
      
   On 2025-12-09 20:11, The Natural Philosopher wrote:   
   > On 09/12/2025 14:50, Carlos E.R. wrote:   
   >> On 2025-12-09 15:09, The Natural Philosopher wrote:   
   >>> On 09/12/2025 11:57, Daniel70 wrote:   
   >>>> On 9/12/2025 9:08 pm, The Natural Philosopher wrote:   
   >>>>> On 08/12/2025 22:39, rbowman wrote:   
   >>>>>> On Tue, 9 Dec 2025 00:20:38 +1100, Daniel70 wrote:   
   >>>>>>   
   >>>>>>> I usually put it down to my Tyres being under-inflated, so their   
   >>>>>>> diameter is less so it takes more revolutions of the tyre to   
   >>>>>>> cover a specified distance.   
   >>>>>>   
   >>>>>> I don't think under inflation would change the diameter enough to   
   >>>>>> throw the speed off that much. In my case the diameter of the 14"   
   >>>>>> wheels is noticeably less than the 15". I see that in the spring   
   >>>>>> when I'm going back to the 15". If I jack the car up enough so the   
   >>>>>> 14" leaves the ground and I can remove it sometimes I have to jack   
   >>>>>> a little more to get the 15" on.   
   >>>>>>   
   >>>>> There is no such thing as diameter on a tyre. It isn't circular.   
   >>>>> Might as well ask yourself 'what is the diameter of a tank track'   
   >>>>>   
   >>>>> What counts is circumference and the tyre is elastic enough to expand   
   >>>>> a little under high pressure.   
   >>>>   
   >>>> .... and that pressure would get higher due to usage heating the tyre.   
   >>>>   
   >>>>> And to wear a little lower.   
   >>>>   
   >>>> ... which would reduce the tyres diameter, so decreasing the Ground   
   >>>> speed.   
   >>>   
   >>> THE TYRE HAS NO DIAMETER., It is not circular.   
   >>   
   >> It doesn't matter. We can calculate it.   
   >>   
   > No you cannot.   
      
   Yes, we can. It is a formula with π in it.   
      
   > Any more than you can calculate the 'diameter' of a tank tread.   
   > You might choose to evaluate (circumference over pi), but that is just a   
   > number that has no meaning in this context. There is no physical   
   > dimension that corresponds to it   
      
   Irrelevant.   
      
   We measure the actual distance travelled for a number of turns. From   
   that we calculate the effective circumference, and from that, the   
   effective radius.   
      
   None of those have to be the apparent length seen by a measuring tape on   
   the wheel.   
      
   --   
   Cheers, Carlos.   
   ES🇪🇸, EU🇪🇺;   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)