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Fs: Potenza Re01r 235/45/17

angel13th
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GH05T Grand Master

GH05T

Posted
Posted (edited)

spaz moment, the 235/40 compared to the 45, this will increase spedo reading yes?

i know only by likr 3-4% but i have a 10% speedo error (always reading to high) anyway

Edited by GH05T
Birds Grand Master

Birds

Posted
Posted

The higher profile will make the car go faster than the speedo is reading, so if your speedo currently reads higher than you're actually doing, it will correct this somewhat...but rather negligible as you say.

Birds Grand Master

Birds

Posted
Posted

Let's not use confusing terms that could be interpreted differently.

Speedo runs off the gearbox output shaft, so it takes its reading based solely on engine rpm and the gear selected, irrespective of what's happening at the tyres and diff. Therefore, 2000rpm in 5th will always make the speedo read the same speed (say ~80km/h) no matter what size tyres or diff ratio you have.

Increase your tyre diameter and the vehicle physically goes faster but the speedo reading stays the same. So if your speedo reads high, putting on larger tyres will make it more accurate. If it reads low, putting on larger tyres will make it more inaccurate.

Birds Grand Master

Birds

Posted
Posted

Manufacturers usually calibrate the speedo to the standard tyre diameter and make it read a little bit high so that they aren't responsible for people's speeding fines.

  • 2 weeks later...
  • 2 weeks later...
GH05T Grand Master

GH05T

Posted
Posted (edited)

received the tires, unfortunately i stuffed up the tire speed calculation (yep did it backwards in my head....derp).
my speedo error reads to high already, the new diameter for my wheels means it will now read higher again not lower so they really dont suit which sucks.

still unfitted
which sucks cos the tread pattern looks so nice

re listed in sa :P

http://www.sau.com.au/forums/index.php?app=forums&module=post&section=post&do=new_post&f=12


Edited by GH05T

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