Keep an eye on your tires' tread depth

**mbeige** · August 25th, 2007 04:58 AM

A good read considering it's the rainy season na. Be safe out there.

Read it all: http://www.tirerack.com/tires/tests/...ay.jsp?ttid=85

Stopping a Car

Even though the speed to begin braking the 3,400-pound BMW sedan was 20 mph higher than the 50-0 mph braking tests we conduct at The Tire Rack, the braking forces developed by the new tires felt reminiscent of full tread depth tires we've experienced on our home track. The car pitched forward as the brakes were applied, quickly took a set and slowed the car with authority. After repeated runs we learned that the average stopping distance for the new tires from 70 mph was 195.2-feet in 3.7-seconds.

Testing tires with the 2/32-inch minimum legal tread depth taught us the probable origin of the driver's accident report statement, "I hit the brakes hard, but nothing happened." There was a perceptible delay while waiting for the braking forces to grow after initiating the stop. Looking at the graphs recorded by the DriftBox confirmed this discomforting situation when we realized we were still traveling at about 55 mph on the tires with 2/32-inch of remaining tread depth when we reached the same distance it took the new tires to bring the BMW to a complete stop! This time the repeated runs taught us that the average stopping distance for the still legal 2/32-inch deep treaded tires from 70 mph had almost doubled to 378.8-feet and took 5.9 agonizing seconds to accomplish. We had the same car and the same brakes, but the tires with minimum legal tread depths weren't able to generate enough traction on the wet road to bring us to a quicker stop.

Stopping a Truck

Then we turned our attention to the approximate 4,500-pound Ford F-150 Super Cab 4x2 pickup. While we expected its additional 1,100 pounds of curb weight to help push the tires down through the water to the road, we felt that the energy required to stop the extra weight would increase braking distances. As with the BMW, we accelerated to the 70 mph target speed on dry road and drove across about 75 feet of wet road before hitting the brakes to begin our panic stop.
While not experiencing as much absolute braking force, the pickup pitched forward a bit more than the car when the brakes were applied, took a set and slowed a bit more leisurely. We learned that the average stopping distance for the pickup on new tires from 70 mph was 255.9-feet in 4.8-seconds.

Testing tires with 2/32-inch of remaining tread depth on the pickup further emphasized the driver's accident report exclaiming, "nothing happened" when they hit the brakes. There was a noticeable hesitation waiting for the braking forces to grow after initiating the stop. Looking at the graphs recorded by the DriftBox showed we initially only slowed 12 mph on the tires with 2/32-inch of remaining tread depth when we reached the same distance at which the new tires brought the F-150 to a complete stop! This time the repeated runs taught us that the average stopping distance for the legal 2/32-inch deep tires from 70 mph was a staggering 499.5-feet in 7.5 excruciating seconds. In addition to the hydroplaning risks associated with shallow treaded tires, this means that the highway would have to be clear for almost 1/10 of a mile ahead of the pickup to allow this combination to complete a panic stop without hitting something.

Stopping with the partially worn tires with 4/32-inch of remaining tread depth again confirmed that the initial stopping forces again felt more like the 2/32-inch deep tires than new tires. Looking at the graphs recorded by the DriftBox showed an improved, but disquieting situation since we were still traveling about 47 mph on tires with 4/32-inch of remaining tread depth when we reached the distance it had taken the new tires to bring the pickup to a complete stop! The runs indicated that the average stopping distance for the 4/32-inch deep worn tires was 377.8-feet in 6.0 seconds, again splitting the difference between the new tires and those that had legal minimum tread depths.

**pup2** · August 25th, 2007 05:19 PM

Ouchy. I had long suspected something of this effect, but what are we to do since new tires are pretty expensive? Dito pa naman basta walang bukol o hindi oblong eh sige na kahit halos wala ng tread.

**dbuzz** · August 25th, 2007 07:08 PM

Originally Posted by pup2

Ouchy. I had long suspected something of this effect, but what are we to do since new tires are pretty expensive? Dito pa naman basta walang bukol o hindi oblong eh sige na kahit halos wala ng tread.

It is true na dito sa pinas uso talaga yung worn or expired tires dahil nga talagang totoong pretty expensive new tires are.

but for sure naman after 4 years of use it already serve its purpose, which normally eh 2-3 yrs ang average usage (sa car ko). That is why we have to make sure that the tires we are buying has, say today, DOM 0107, bale 1st week ng January 2011 ang expiry nun mga 4yrs from now.

well, mahirap na yung ala-tsamba ang buhay mo, buhay ng passenger mo at yung mga collateral damages nun.

**mikey177** · August 25th, 2007 08:14 PM

Yes, the price of new tires is a small investment compared to the lives of my loved ones. Dito pa naman sa probinsya, madalas magkaroon ng water buildup sa iba't-ibang portion ng highway between Tarlac and Pangasinan. This poses a danger not only because of increased stopping distances, but because of the risk of aquaplaning too.

**mbeige** · August 26th, 2007 03:12 AM

Consider this: other cars and drivers do not care (truck, PUV, etc) about safety basta may pasahero ayos na yon. If they are the ones who lose control it's important that you can also avoid it especially kapag bumabiyahe.

I just realized our '92 Corolla's tires are near the limit gamit kasi yon araw-araw halos. We can get cheap ones installed just make sure walang "negative feedback" sa brand (like Firestone here in the US, and their exploding tires).

Part of owning and driving a car is the responsibility to ensure that your tires are in good shape. After all, those four contact points are probably the only things keeping you from flying away.

**pup2** · August 26th, 2007 06:03 PM

Isa pa, may expiration ba talaga ang tires? Sa totoo lang after 4 years, napansin ko madali magbawas ng PSI ang tires ko kahit di pa masyado pudpod. Usually pinapalitan ko lang ang pito -- although pag may imminent long drive ako, pinapalitan ko 2.

Kung talagang may expiration gaya ng suspetsa ko, bakit walang naka-indicate sa gulong gaya ng sa perishable products?

**hominid** · August 26th, 2007 09:38 PM

Dapat nga naman maglagay ang mga manufacturers kung talagang meron.

Ang pagkabasa ko, may statistics daw na lahat ng blown tires eh 4 yrs older. So basically, iwas lang risk yan at d talaga expired na. Kung cguro ang gamit mo sa sasakyan mo eh, mga 40kmh lang, I think u can take the risk.

Anyways sa mga PMS sched naman, 2 yrs lang for replacement na ang tires. Maghanap na lang ng mura pero ok. Usually mga made in India. Me thread na dyan.

**dbuzz** · August 27th, 2007 04:18 PM

Originally Posted by pup2

Isa pa, may expiration ba talaga ang tires? Sa totoo lang after 4 years, napansin ko madali magbawas ng PSI ang tires ko kahit di pa masyado pudpod. Usually pinapalitan ko lang ang pito -- although pag may imminent long drive ako, pinapalitan ko 2.

Kung talagang may expiration gaya ng suspetsa ko, bakit walang naka-indicate sa gulong gaya ng sa perishable products?

Originally Posted by hominid

Dapat nga naman maglagay ang mga manufacturers kung talagang meron.

Ang pagkabasa ko, may statistics daw na lahat ng blown tires eh 4 yrs older. So basically, iwas lang risk yan at d talaga expired na. Kung cguro ang gamit mo sa sasakyan mo eh, mga 40kmh lang, I think u can take the risk.

Anyways sa mga PMS sched naman, 2 yrs lang for replacement na ang tires. Maghanap na lang ng mura pero ok. Usually mga made in India. Me thread na dyan.

Wala nga pong expiration date DOM lang. sa ibang research nagsasabing 4yrs lang then iba 6yrs naman at expired na ito nga sa USA ay pinaguusapan yan kasi nga totoo namang it's an invisible hazard eh, "The industry knows a lot about it, and they have recommendations pero inilihim nila yun from the public for years. kaya dapat lang na maglagay sila ng expiration date the same as just about every other product, from food to paint, has an expiration date on it.''
pero may drawback kasi daw manufacturers are concerned that putting an expiration date on tires would create a false perception that newer tires are safe, regardless of driving conditions, maintenance or wear. so aywan ko pero para sa akin dapat lang na may exp date yun.