Increasing tyre pressures by 20% for economy??? - Dr_Rubber
The EU will be introducing mandatory TPMS (tyre pressure monitoring) shortly as a way of reducing CO2 emmisions (low pressures increase CO2 and many people don't check).
The other suprising way tyres alter mpg is profile. The frontal area of a tyre has a big affect on drag! thats one reason Prius's have skinny tyres.