Tire replacement

Is there a rule-of-thumb when to replace tires? All four are evenly worn with about 1/4" depth in the groves. We’ve 51K on oyr 2007 van, but boought it from a dealer with 22K on it, so tire origin is unknown.

There are wear indicators molded into the tread at several locations around the tire. When the tread wears down even with the indicators it’s time to replace the tires. Check your owner’s manual for information about this.

You can also use a quarter to measure the tread. Stick the top of the quarter into the tire tread. If none of George Washington’s hair is covered by the tread, the tires are ready for replacement.

For all sorts of good information about tires, tire wear, how to measure tread depth, etc, consult the tech section of http://www.tirerack.com

Thank you! Exactly what I needed.