[bengascoyne]

Quote: Originally Posted by Ant FR (original)

Rolling resistance, simple physics.

More friction, more energy sapped from rotating ing wheel, thus more energy required to turn it. In laymans terms.

However tread pattern may have more effect than the actual aize. Thats why cars such as the bluemotion passatt have specially designed treads that increase fuel economy.

could go on for years. but simple test, get your little finger and push it across your desk, now do the same with your thumb, and you will feel the difference, larger area more friction, more energy required.

So in essence, when am changing my tyres (which need doing soon) I need to make sure am getting tyres of similiar width to try and keep any changes to a minimal, which am assuming they would be anyway, even in extreme cirumstances.