It really depends on the type of tire youhave (all-season, winter, etc). Technically speaking, once the tire is worn down to 2/32nds, they are worn too low. But a quick and easy way to know if your tread is too worn is to use the rule of the penny. Take a penny and put itinside the tread groove so Lincoln is doing an unside down dive into the tire. If you can see the top line of his head, it's time to get new tires.
This is a great visual for you describing what I said above:
The best thing to do if you aren't sure is to take it in to a dealer and ask them to check for you.
And when you are ready to buynew tires, this is a great guide:
Or check out an article we posted on Ask Patty:
Selecting The Right Tire: As Simple As Selecting The Right Shoe
Wearing sandals in the snow is not appropriate. Running shoes for a
formal occasion would be very out of place. Just as proper footwear is
important to your comfort and correct body alignment, appropriate tires
are vital to affecting the overall performance and handling of your
inappropriate tire provides little benefit to the vehicle it supports.
A sporty sedan offers little excitement if not supported by properly
designed and fitted tires. It makes no sense if you are seeking optimum
performance to purchase inexpensive tires, just as it makes little
sense to wear the wrong size shoes.
choosing tires, just like shoes, look for the proper fit.
Understanding tire markings can help you select the right tire for the
right job. With the on-going popularity of light trucks and SUVs, tire
manufacturers have worked diligently to offer many tire options.
tire marked “A/T” is designed for all-terrain use but also performs
well on the highway. An all-terrain tread has many independent blocks
separated by large grooves for off-road traction. Varied sizes and
shapes of tread blocks minimize highway noise. The A/T could be
compared to a tennis shoe: comfortable and dependable, but only able to
handle mildly rugged conditions.
An A/T tire might offer
options that an off-road enthusiast would enjoy, but it is not as
aggressive as the M/T tire. A tire designated with an “M/T” is used
for “Max-Traction.” These dutiful soldiers easily handle muddy and
rocky surfaces frequented by the serious adventurer. The M/T tire is
the “hiking boot” of tires. Luggy, rugged tread elements with large
tread voids offer excellent traction to handle the most severe driving
An A/S denotes all-season tires which are dependable for many road
conditions. For severe snow conditions, a mountain snowflake
pictograph with an M+S represents the industry’s standard for tires,
much like snow boots, designed for wintry conditions.
selecting tires, don’t be intimidated by the choices. Think of it as a
chance to shop for shoes – but for your automobile. Search for
comfort, style and performance to suit your personal driving habits.
up options by visiting your local tire dealer or retailer, the
professionals who want to help you “put your best foot forward.” For
more information visit Bridgestone Tires, the Tire Safety website, or phone the Bridgestone Firestone customer service representatives at 1.800.807.9555.