I need to know....

[7-Dog]

So, if the odometer mechanism is soley dependent on number of wheel revolutions to count distance travelled,

if you increase the wheel diameter you'll actually be covering more kilometres than your odometer is counting?

Look at it this way;
Current circumference for example 1m, increase the diameter therefore circumference might go up to 1.1m. Odo still counts 1 revolution as 1 metre, but you are actually travelling 1.1m.

I was always under the impression that changing RIM's affects the wheel rotation and can have an affect on your odo.

With what Rams52 has said, wouldn't the "normal" inflated tyre travel 1 metre. Therefore before it was pumped up, it was travelling 0.9metres - in the scenario you mentioned?

With regards to fuel efficiency, I can only relate it to riding a bike. It is a lot harder to ride a bike with tyres that are under inflated compared to one inflated correctly.

[Psyber]

Any change that increases the diameter of your wheel and tyre combination increases the circumference of the combination and has the effect Rams52 described.
From the Michelin site, a 205/55ZR17 tyre and wheel combination has a diameter of 658mm and a rolling circumference of 2006mm.
So, 5mm of extra tread makes a 0.76% difference to the diameter and reading as C = Pi x D.

This will effect both Odometer and Speedometer accuracy!

[Ian]

I was always under the impression that changing RIM's affects the wheel rotation and can have an affect on your odo.

If you increase your rim diameter and fit lower profile tyres, with the right profile choice you could end up with the same rolling diameter, this would give no change.

If the tyre profile is low enough, even with a larger diameter rim you will have a smaller rolling diameter which will give you higher KM travelled on the odometer than actual distance travelled

If the rim size is increased and the profile stays the same or is higher you will definitely have a larger rolling diameter, your odometer will show that you have travelled less that the actual distance travelled

Going from no tread to full tread on identical tyres will also increase rolling diameter

[Gingernuts]

This thread is making my head hurt.

[The Ash Man]

This thread is making my head hurt.

I'm tYred of it too

[Booney]

This thread is making my head hurt.

I'm tYred of it too

Trust you to wheel out that old one.

[The Ash Man]

This thread is making my head hurt.

I'm tYred of it too

Trust you to wheel out that old one.

Yeh I had to tread carefully though

[Q.]

Geez, are you lads driving another thread off track again

[The Ash Man]

Geez, are you lads driving another thread off track again

You seem to be aligning yourself with us

[Booney]

Geez, are you lads driving another thread off track again

You seem to be aligning yourself with us

Nicely balanced..

[The Ash Man]

Geez, are you lads driving another thread off track again

You seem to be aligning yourself with us

Nicely balanced..

This thread has lost its bearings

[Ian]

The wheels have well and truly fallen off!!

[White Line Fever]

You guys just keep going around in circles

[Big Phil]

Just stop - it's driving me nuts

[Drop Bear]

Yeah, give it a brake fellas.

[Mr Beefy]

I reckon they could go on like this for a goodyear

[smac]

It'll burnout long before that.

[fish]

This thread is getting wheely stupid!

[Psyber]

This thread is on a Michelin of Falken self-destruction, continue at your own Pirelli..

[Q.]

This thread is on a Michelin of Falken self-destruction, continue at your own Pirelli..

You win