When was the last time you replaced your sneakers?

[Kevin]

Why - when the speed is accurate so is the odometer!

[Ben Up North]

No no no!

in Australia cars prior to 2006 could have the speedo up to +/- 10% out, but the odometer was only allowed to be +/-4%. (but you're not allowed to have the car travel faster than the speedo reads so the speedo can never read slow)

It's similar since then, but no longer is any consideration given to the accuracy of the odometer.

They're certailny not required to be as accurate (or as inaccurate) as each other.

The only way to really tell is to drive a known distance and check what the odometer reads.

Fortunately, there's a speedo check section of road near here that covers a measured 5kms, with 1km markings, so it makes it easy for me.

A good GPS will enable anyone to do it easily, zero off your trip meter, drive a distance according to the GPS and check your odometer to see what the difference is (or the other way around, set your GPS to track you and drive Xkms according to odometer, see what the GPS says you've travelled)

[Kevin]

I'm confident that with increased tyre size my Forester speedo and odo are accurate. I too pass a speedo check section every now and then and it is OK.

[Ben Up North]

Which means prior to putting on the increased tyre size you were being ripped off on servicing (potentially)!

[Kevin]

I think we get ripped off regardless of tyre size!

I do most of my own servicing.

[MiddleAgeSubie]

Originally Posted by Bridgestone

Hi @MiddleAgeSubie,

Thank you for the inquiry. We've passed this question on to the technical team and will be back shortly with an answer.

Kind Regards,
The Bridgestone Team

Thanks! Let me know what they say.

[Bridgestone]

Originally Posted by MiddleAgeSubie

Thanks! Let me know what they say.

Hi MiddleAgeSubie,

Our technical division's reply:
The diameter of a tyre is primarily dependant on the inflation pressure.
If a tyre is under-inflated, it’s diameter will reduce.
However, the inflated ‘appearance’ of a tyre also changes depending on the aspect ratio (profile) of the tyre, ie a ULP tyre will not appear to be under-inflated
due to the stiffer sidewalls.

Kind Regards,
The Bridgestone Team

[Rally]

@Bridgestone any luck on the information I asked for?

[Rally]

Originally Posted by Bridgestone

Hi MiddleAgeSubie,
a ULP tyre will not appear to be under-inflated
due to the stiffer sidewalls.

Kind Regards,
The Bridgestone Team

Would the RE003 have those stiffer sidewalls?

[ateday]

I agree with Kevin.
Replacing the original 65 profile tyres on my MY03 Forester with 70 profile made the speedo pretty accurate as checked against the road 5 km tests and the GPS.
Odometer I don`t worry about too much as I do/get regular services. It seems to work as at 359000 kms the heads have not been off nor does it consume vast amounts of oil. More seems to leak from the rear engine oil seal than it burns. Changing the oil every 5000 km means it needs about half a litre top up between changes.