Featured America's Tire

So in an emergency, how well do you think your anti lock brakes will handle the mismatched treads? And you are really wanting to be running around on 8 year old tires?

I replaced mine at 5+ years with 35k on them. I've seen too many accidents with fatalities caused by old tires.

 

How many miles have these tires done?
What is the groove depth left?
A small value is dangerous when driving at high speed on a section of road covered with water.

 

Measure in 3 places across the width of the tire. The lowest depth is the one you use in comparing tread depth. You can find the original tread depth in the "specs" area for each tire at Tire Rack. Their site has videos showing how you can measure using a coin and what the recommended tread depths are and how they affect handling. Or you can buy a "professional" tread-depth gauge from most auto parts stores for around $3.

You could read their tests or I'll cheat and just give you the results. The difference between a new tire and one worn down to 2/32 (legal limit in many states) in a test on a water soaked surface was an almost doubling of stopping distance! 4/32 deep tires took about 50% longer to stop than new tires.

New - 195 feet

4/32 - 290 feet

2/32 - 378 feet

Even more startling to me is that on a 2/32 tire, in stopping tests in the wet from 70MPH the new tire would have stopped the car where the worn tire would only have slowed the car to 55MPH!!!! 4/32 would only have slowed the car to 45!!!!

They don't cite skidpad tests but the same issues that affect stopping distance would affect your staying on the road as you round the curve in the very wet. The tire needs the depth in order to evacuate the water beneath the tread and get the tire "rubber" into contact with the pavement. If it rides up on the water, it is like driving on ball bearings. I recall driving behind a car once and seeing it hit a puddle just as it came to a bridge and then going off like a pinball bouncing off the sides of the bridge. When I stopped, sure enough balding tires.

Depth does matter in the wet.

In the dry, depth is not nearly as important as long as the depth is consistent.

Which is why I am overly .... about replacing tires.