How often to buy Tires?

Age is unimportant. Tread wear and damage is what you look for.

I was taught to use a penny as a gauge.

Take a penny and turn it with Abe's head toward the tire. Put it into each groove in the tread. If the top of Abe's head is just slightly covered by the raised part of the tire, your tire is still legal. However, do not just do this in one groove. Go across the whole tire making the same test.

The link below will explain this whole matter for you.

Tires should be replaced every 4-5 years whether they still have life in them or not, the rubber drys and starts to slowly rot, leading to an unexpected tire failure. That's how Paul Walker died. The garage queen Porsche Carrera GT had its original tires from 2005.

Depending on how much you drive, how you drive, tire brand, tire type, and driving terrain you could be buying tires every couple of months. You should buy tires whenever the tread bar appears.

For me tires last about 2-3 years before i get new ones depending on how much i drive each year. during the winter(3 months) i have a set of snow tires on the car so the all seasons get don't get used.

It's possible you have to replace it. It depends on how much wear it has. Like the other guy said below 1/8" you need to replace the tire because wet traction is highly compromised.

As for age. You look signs of dry rot. Basically the rubber has dried a big and you'll see a little bit of cracking. This could happen on tires 5 years and older.

You should buy new tires when the tread wears out. If you take good care of your tires and rotate them and keep them in alignment and balance then you should be able to get about 50K miles out of them. It can also vary depending on how you drive. You can't really go by years.

Depends on how many miles you do a year, what you use the car for, how you drive the car, what make of tyres (Some are better quality) etc etc. Just check the tyres over, make sure there's no damage to them or they're not cracking or split and that the thread depth is still above the legal limit.

In general, you should consider replacing your tires when the tread depth dips below 4/32. Or, if your tires are showing uneven wear, cracking, cupping, feathering, or dry rot. Age or mileage may or may not be a factor because all tires vary greatly in quality and tread wear longevity.

I buy 2 once a year just as winter hits.

As often as you need them.