The Penny Test for tread

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All but 2/32"
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Originally Posted By: Kestas
I think the penny test went away with the introduction of wear bars molded in the tire.


What date code were there bars introduced?
 
Originally Posted By: TechnoLoGs
What date code were there bars introduced?

Wear bars have been mandatory in the US since about 1968.
 
Originally Posted By: gaijinnv
All but 2/32"
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I just read that the penny test is not good, that you actually should replace tires at no less than 4/32.
 
Originally Posted By: TallPaul
I just read that the penny test is not good, that you actually should replace tires at no less than 4/32.

Yup. 2/32" is a legal limit, which does not necessarily mean it's safe.
 
I bought one of those little tools to measure, penny is probably fine though.

Might be wrong, but thought modern best practice was to not see the top of Lincoln's head when inserted on the wear bar???

That would align with the 4/32 above I'll bet???
 
The penny test is pointless and obsolete. Forget you ever heard about it.

Wear bears are a much better indication, and don't depend on the measurement technique on curved-bottom grooves.

Even then, common sense should prevail. If you have snow or heavy rain, replace before down to the wear bars.

If you really care, digital depth gauges are now really inexpensive, well under $10. They have a better chance of measuring the center of the groove, and are easier to read. Plus they are very useful for measuring other things.
 
The coin tests are fine if you're in a pinch. You can't tell how much depth there actually is just by "looking for the tire wear indicators". A tread gauge is best, as you can also guess your approximate tread life % from the original depth.

I have a Milton tire tread depth gauge that was handed down from my dad. He told me he probably bought it back in the 1980's. It's a small, all-metal gauge that measures up to 1" (0/32"-32/32").

My AccuGage tire pressure gauge is also pretty old (bought it back in 1995). Still reads within ~2psi of most newer gauges.
 
Many new tires already have wear indicators. Nokian shows remaining tread depth in 2 mm increments. Continental marks if they feel there's enough tread for safe dry, wet, or snow use.

At a tire shop I saw an employee use a tire tread depth gauge when I had a blowout and he wanted to measure how much tread was remaining to prorate the road hazard warranty. I suppose that they have similar gauges available at chain checkpoints when "snow tread" tires can substitute for chains with adequate tread depth.
 
The nokians that show tread depth are pretty cool! I need to check to see if my parents Nokians have that.

The Vatiiva on my Cherokee do not have that
 
A tread depth gauge is less than US$5. It makes it really easy to measure the tread depth at various places across the tread.
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The legal limit in my state is 2/32" except 4/32" for snow tires. I feel that both are a death wish.
 
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