Generally, when the tread is worn down enough that it becomes flat in some spots.
Things you can do to make your tires last longer:
ALWAYS keep them aired properly. In warm weather, go about 5-10 PSI lower.
Have your tires balanced (all four) every 5,000 miles.
Have a shop rotate the tires.
Keep the wheels aligned, and go slow over big bumps and curbs to keep the wheels in alignment.
Why should I have my tires rotated?
Front And Rear Tires Wear Differently
Think about it. All that parallel parking. All those three-point turns. With each turn of the steering wheel, pressure is brought to bear on the front tires. (This is even more accentuated in front-wheel-drive cars, where the front wheels also supply the main motive power for the vehicle.) Resistance causes friction, which in turn produces heat. The result? The front tires wear quicker than the rears.
Because of this, it's necessary to rotate the tires front-to-rear several times during their life cycle to 1) equalize tread wear and 2) maximize the life of the tires. This is what we refer to when we say "rotate the tires."
Tips to make your tires last:
Keep ‘em in line!
Pot holes, speed bumps and curb checks. All these things can throw off your alignment which can make your tires wear down unevenly. So have your front end alignment checked at least every couple of months.
How often should I rotate my tires?
That depends. Refer to your owner's manual for exact guidelines, but most manufacturers recommend rotating tires roughly every 5,000 to 10,000 miles. Again, see your owner's manual for specifics.
How often should I get my oil changed?
At least four times a year or every 3,000 miles. Although you oil may last longer than this it's a good idea to have your car looked at every so often to make sure everything is in top working condition and an oil change is the perfect time to do it.
Some Fuel Saving Tips:
These fuel-savings tips come from the Car Care Council. You can also get helpful hints from the federal government. Also check the “scheduled vehicle maintenance” section of your vehicle’s owner’s manual.
How do under-inflated tires affect fuel efficiency?
Under-inflated tires and incorrect wheel alignment can lead to conditions that increase rolling resistance. This is like driving with the parking brake on and it can cost a mile or two per gallon on a car that normally gets 20 miles per gallon. Correct tire inflation pressure is critical for good fuel economy, safety, maximum tire life, and proper handling.
How do dirty air filters affect fuel efficiency?
An air filter clogged with dirt, dust and bugs chokes off the air and creates what is called a “rich” fuel mixture – too much gas being burned for the amount of air, which both wastes gas and causes the engine to lose power. Replacing a clogged air filter can improve gas mileage by as much as 10 percent.
How important are vehicle gas caps?
17 percent of the vehicles on the highway have either misused or missing gas caps, causing over 147 million gallons of gas to vaporize into the atmosphere every year.
Why should spark plugs be replaced regularly?
A vehicle can have either four, six, or eight or more spark plugs, which fire as many as 3-million times every 1000 miles, resulting in a lot of heat, electrical and chemical erosion. A dirty spark plug causes misfiring and that wastes fuel.
Does keeping a vehicle in tune save fuel?
Keeping up with regular maintenance, including today’s maintenance tune-ups can help improve gas mileage by an average of 4.1 percent. Results vary based on the vehicle, the extent of the maintenance performed and the climate in which you drive.
Driving Habits to Improve Fuel Efficiency:
•Avoid quick or “jackrabbit” starts and stops
•Aggressive driving wastes gas – it can lower your mileage by up to 33-percent on the highway and 5-percent in the city
•Observe the speed limit – gas mileage decreases rapidly above 60mph.
•Avoid excessive idling – idling gets 0-miles per gallon.
•Use cruise control because it helps you maintain a constant speed.
•Use overdrive when possible to reduce engine speed and engine wear.
•Avoid carrying unneeded heavy items in the trunk, as an extra 100 pounds in the trunk reduces a typical car’s fuel economy by 1-2 percent
•Use air vents to circulate fresh air instead of using the air conditioner
