Different tires have different lifespans on them. They say if you stick a penny upside down into the treads of the tires and you can see the top of Lincoln's head, it's time to replace them, but I feel you still have a bit of life left on the tires. If there is any baldness where treads used to be, you need to go on and replace them. I had to replace the tires on my girlfriends Neon last week. Sam's had B.F. Goodrich with a 50 dollar rebate when you buy 4. The warehouse clubs are some of the least expensive places to buy tires. Also check out tirerack.com and have them delivered and installed to save a bit if you're not in a hurry for new tires.
You should buy new tires when the tread or sidewalls on your old tires show wear or cracking. Tire tread depth should be at least 1/16 of an inch. A good way to test this is to stick a penny into the tread so that the top of Lincoln's head is pointing towards the tire. If the tread covers part of his head there is enough tread. If you can see all of Lincoln's head it's time for a new set of tires.
Most tires are rated for 40,000 miles or so. This varies with the quality of the tire. You should have a minimum of 1/8" tread depth all the way across the width of the tire. Any less and the tires need to be replaced. For more information, visit www.tirerack.com . There is a really good article about stopping on tires with 1/16" tread vs. stopping with 1/8" tread there.
It pays to shop around. Ask for a "drive out" price on a set of 4, including new valve stems, installation, balancing, road hazard warranty coverage, and free rotation for the life of the tire. You can choose from tire designs that are for long mileage or performance (wet and dry adhesion, cornering, etc). Also, there are high performance tires for sports cars, tires for off-road use on SUV's, etc. A noisy tread design should be considered. Consumer Reports is a good source for test results. Do not allow price to be your primary consideration. Just remember: your life is riding on your tires. Costco is a good source, as Michelin oversees their tire departments. Michelin developed the radial tire and still is the manufacturer with the best track record for producing a quality trouble free product.
You should be driving "A" or "AB" quality tires. I buy from a used/2nd market Tire place (have done so for over 25 yrs}. Save a fortune especially on the higher range tires. But, know who you are buying from. Women, especially, can really be "taken!'
I have a '07 Pontiac G6 GT HardTop Convertible with only 26,400 miles on my after market tires. I live in the city & everything I need is within a 5-6 mile radius. My driving habits are, infrequent trips with many stops. My car may sit for days before I have to go out. I work from home so I don't Need to go out. NOW~ my High Performance Tires have DRY ROT. Warranty coverage does NOT cover DRY ROT. Evaluate your driving habits & consider DRY ROT. ALSO~I agree "IT PAYS TO SHOP AROUND." Being a Woman, know what your talking about, to help avoid getting 'taken.' Before you make your calls to diff shops make sure to WRITE DOWN ALL THE INFO about your tires. This info is written on each tire along the sidewall. Having this info on hand will help you sound knowledgeable & sure of what you want.
One important thing to remember when replacing tires is always look at the vehicle identification system sticker in the door jam or glove box of the car..this is very important, for example a 2010 ford focus requires a (z rated) high speed radial, not because the car is capable of 150 m.p.h. but because it requires that type of tire to handle correctly and it also dramatically affects braking ability. Another example if this is as follows, you buy a used pickup truck. the truck requires a l.t. designated load range, but you have a p. metric car tire on it, it might not be enough to handle much more than the weight of the truck when it is empty.. tire size and type are very important.