I recently changed from an Octavia Elegance 2.0L Diesel (72000 Miles)to a 2.0L L & K Diesel(17000 Miles)

Previously I was getting 50mpg Now I am getting 45mpg.

The only diffeence as far as I am concerened is the tyre size.

Previously I had 205/55 16"

I now have 225/45 17"

Would I need to change the rims if I wanted to put 205/55 16"?

Would be interested in any comments from you knowledable Gentlemen (or lady!)

Being the L&K with lots of toys/leather is the new car heavier?

At 72000 miles your previous car will have a nice loose engine which aids economy, however 17000 miles the engine is still quiet tight and its MPG will continue to improve. Winter diesel will also hinder fuel economy due to the agents added to the fuel to stop it waxing.

Is the new L&K a PD also or a CR?

Tyre size WILL make a difference, the larger the diameter of the wheel the heavier they are, a 225 will also have more rolling resistance than a 205, the heavier something is or the more rolling resistance it has will require more fuel to move it.

I now have 225/45 17"

Would I need to change the rims if I wanted to put 205/55 16"?

eerm yes, you cannot fit a 16" diameter tyre onto a 17" diameter wheel.

Tyre sizes explained

Consider possible side effect on speedo accuracy of changing wheel/tyre size ??

I replaced my 205/50/17 with 225/45/17 on the front of my octy and lost roughly 5mpg. When i put my winters on which are 195/55/16 i gain just under 5mpg

You could try fitting 205/50/17 instead of the 225's?

Lots of factors to blame.

Same make and model can produce variations in fuel consumption, so change of model seems natural to me to have some fuel variation.

As said heavy body, heavy right foot to compensate difference for instance.

Tyre size WILL make a difference, the larger the diameter of the wheel the heavier they are, a 225 will also have more rolling resistance than a 205, the heavier something is or the more rolling resistance it has will require more fuel to move it.

+1 yup, fat tyres = more rolling resistance = lower mpg

Very many thanks for your replies Gentlemen. It is very much appreciated.

My own thoughts were the additional resistance owing to the larger tyre.

I would very much like to hear from anybody who has tried the idea put forward by

Raf who suggested trying 205/50 17"

It is my third Octavia, and without doubt, the overall performance is fantastic.