George Washington is legendary for many reasons, but he may be adding a new posthumous distinction as a tire tool, based on recent tests.

Traditionally, tire-wear advice has been to measure the tread depth using a penny, with Abe Lincoln’s copper head at 2/32-inch being the universal signal to replace a car’s rubber. However, Consumer Reports general advice has been for people routinely driving in heavy rain or winter conditions to consider replacing the tires closer to the 5/32-inch groove depth, which marks the half-tread point on many tires.

Recent testing by retail giant The Tire Rack confirms our long-standing guidance, and their recent PR campaign is getting this important advice to consumers. As they put it, using Washington’s head on a quarter (which represents 4/32-inch tread depth) may be a better gauge of when a tire’s traction has diminished significantly. We agree.

Using a 2006 BMW 325i and 2006 Ford F-150 Super Cab 4x2, The Tire Rack tested original fitment tires in new, 4/32-inch, and 2/32-inch conditions. The wet braking results show a dramatic difference that should be a real wake-up call for motorists. (Read the full report.)

While most states consider 2/32-inch to be the legal limit, lead by the federally mandated tread-wear indicators, we recommend replacing tires sooner for those typically driving through poor weather. Right now, our tire engineers are validating data from an extensive tire-wear performance test to be posted online in the weeks ahead. In addition, the latest ultra-high performance tire tests to be published, and posted, in a couple months will report on the most extensive tread-wear testing performed by a North American consumer publication. From the combined results, we’ll provide advice not only on when to buy, but also how to select a tire that will give the best performance and most miles for your application.

To learn more about tread-wear safety, read our updated report “How safe are worn tires?"

--Jeff Bartlett