[aerohead]

All the show cars and concept cars that get great mpg have special,low-rolling-resistance(LLR) tires.These particular tires are not in production and are not for sale,however,for the tires that are available to the general public,there is a "range" of coefficient of friction(Fr) for the tires available.------------------------------------------A 10% reduction in rolling resistance will net about 3.8% improvement in mpg,for comboned city/hwy driving.------------------------------------ Neglecting your tires,and letting the cold inflation pressure drop 25%,will cost you 1 mpg.-------------------------------- overinflating your tires 25% will net you a 1% improvement,but could destoy the tire,throw you out of control,and kill you,your passengers,and anyone else around you.------------------------------------ Tire manufacturers recommend that you never exceed the maximum pressure embossed on the tire sidewall.--------------------------.Also,it takes about 5-miles (8 km ) of continuous driving to get your tires up to their equilibrium temperature and highest economy.If your car is OBD-2,and should choose to monitor your mods with a Scan-Gauge,bear in mind,that any testing done without a 22-mile (35 km ) warm-up drive,will yield erroneous data,compared to a fully-warmed-up vehicle.In addition to the 5-miles necessary for the tires,all your lubricants will be below their equilibrium temps(and best performance) without at least 22-miles(35 km ) of warm-up.