Last week I talked about why you shouldn't buy studded snow tires. This week I'm going to talk about why you might need new snow tires.
Tread depth is very important to tire performance. In racing, you want as little tread depth as possible. Which is why most race car tires don't have tread as all. In Europe, they drive in the rain and have tires with tread for that purpose. In the U.S., we don't race in the rain. Tread makes a tire wobble in corners, which means you have to go slower in corners. Thus, the effort to avoid tread in racing.
But we aren't racing. We're driving on the street. Legally, you have to have at least 2/32nds of an inch of tread depth. Anything less than that is illegal.
You can test this with a penny (hey, they are useful for something). Put the penny in the tread with Lincoln's head down, touching the bottom of the groove. If all of Lincoln's head is visible, you need to replace those tires because you have less than 2/32nds of an inch of tread.
But, to be practical, if you're planning on driving in rain and/or snow, I personally recommend at least 6/32nds of an inch for a snow tire or a regular tire in the winter. I base that on advice from Tire Rack. Yes, Tire Rack wants to sell tires. But they have always been very honest with me.
So, before winter hits, measure your tread depth. If you don't have a tread depth measuring tool, any tire store will likely measure your tread depth for you for free. Yes, they want to sell you tires.
I measured mine and they are at 9/32nds. So they will last one more winter.