Print 23 comment(s) - last by mindless1.. on Jun 14 at 3:03 PM

Tire pressures play a big factor in accidents

A government study performed in the United States has found that 5% of vehicles involved in crashes experienced some sort of tire problem. The moral of the study is that underinflated tires are at significantly higher risk of causing an accident. The National Highway Traffic Safety Administration -- using data gathered between 2005 and 2007 -- conducted the study.
According to the study, vehicles with tires underinflated by 25% or more were three times as likely to be involved in the crash linked to tire problems. The study also found that 66% of tire related crashes involve passenger cars.
"Tire problems are inherently hazardous to vehicle safety," the NHTSA report said. "When these problems emerge in the pre-crash phase, the time window for attempting a crash avoidance maneuver is normally very small."
Another discovery made in the study includes that poorly maintained tires are tires that are underinflated are also more likely to experience problems in bad weather.
Of the sample vehicles that the study looked at it was determined that 11.2% had problems linked to tires in bad weather compared to 3.9% when weather was not a factor. Senior vice president for public affairs cites the new tire study for the Rubber Manufacturers Association, Dan Zielinski, as a clear indication that proper tire maintenance and inflation are critical for driver safety.
Tire pressure monitoring systems are installed in all 2008 model year and newer vehicles due to a U.S. government mandate. The tire pressure monitoring system alerts drivers when any tire is 25% or more below the recommended inflation level.

Source: Detroit News

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RE: car vs tire manufacturers
By gcor on 5/20/2012 8:45:28 AM , Rating: 2
Actually, I found out it's more complicated than that, as % of load rating needs to be factored in.

As we were going to be spending a lot of time off road on poorly maintained tracks, I picked up some light truck all-terrain tires with 10-ply rated side walls.

When I looked for the recommended pressures for the new tires, it was explained to me that if a tire is carrying less than the load rating, then the recommended pressure needs to be suitably adjusted. The rule-of-thumb formula I was told was;

min-psi + ((max-pis - min-psi) x % of load rating).

eg. 40 + ((80 - 40) * .6 ) = 64

This means you need to know how much each wheel is carrying, which changes on front and back axles. For me, this meant a trip to a weigh bridge as the car was heavy modified, plus we often had the ball weight of a camper trailer to add.

RE: car vs tire manufacturers
By mmatis on 5/22/2012 8:26:40 AM , Rating: 1
The car manufacturers call out inflation pressure based on THEIR priorities. Remember the Ford SUV rollover problem a few years back with the Firestone tires? Ford called out a low inflation pressure for the tires to make the ride seem less harsh. And then, of course, many in the motoring public never even bothered to keep their tires at THAT pressure. Greatly increased sidewall flex caused tire failures, resulting in rollovers. And Firestone got the blame.

If you really want to do this right, you need to look at not only the load you run with compared to the rated load for the tire (which is based on the max inflation pressure) but also the rim width you are using compared to the recommended width by the tire manufacturer for that model and size tire. Those of you calling for increased tire pressure will pay for it in early tire replacement, as overinflating the tire for the load carried and the rim width will result in your tires wearing out in the middle of the tread early. By the same token, underinflation for the load and rim width will cause early wear on the outside edges of the tread. A tread depth gauge is a worthwhile investment.

And one further note of interest. Where water depth on the road is greater than tread depth, full hydroplaning can occur at speeds roughly equal to 9 times the square root of the tire pressure. That means 35 psi tires may fully hydroplane at under 55 mph, while 81 psi load range
E tires won't hydroplane until over 80 mph if fully inflated. Of course, the dry road performance, as well as the ride, of those 35 psi tires is FAR better, but...

RE: car vs tire manufacturers
By mindless1 on 5/23/2012 7:54:13 PM , Rating: 2
THANK YOU! I was laughing quite a bit about all the posts on this topic by people who feel superior about knowing how to decide the right tire inflation level when they did not know themselves.

RE: car vs tire manufacturers
By hangfirew8 on 6/11/2012 2:20:32 PM , Rating: 2
Ford called out a low inflation pressure for the tires to make the ride seem less harsh. And then, of course, many in the motoring public never even bothered to keep their tires at THAT pressure. Greatly increased sidewall flex caused tire failures, resulting in rollovers. And Firestone got the blame.

Wrong. There was a lot more to the Firestone/Explorer problems than recommended tire pressure. Firestone made defective tires prone to tread separation- Goodyears running at the same pressures on the same vehicles had no such problem. Ford made a poorly balanced vehicle. Together they created a serious liability problem for the manufacturers.

Firestone was found to have a long history of labor and quality problems in their Decatur plant, and Ford in Venezuela was already recalling the Explorer for refits to deal with the rollover problems. Both companies knew about the problems and tried to silence everyone hurt with settlement agreements. Finally someone refused a settlement offer, went to the media and blew the lid off the case.

Both statistically and through experimentation, it was found that all other SUV's in the road were more tolerant of blowouts and less likely to roll over than the early Ford Explorers.

RE: car vs tire manufacturers
By mindless1 on 6/14/2012 3:03:32 PM , Rating: 2
It's sort of irrelevant. Semis are more prone to rollover and lose tire treads all the time. The problem was mostly that drivers were migrating to SUVs from cars and did not adjust their driving style to factor for a more top heavy SUV.

Yes Ford could be blamed a bit for not making the top as light as possible in the interest of safety but no matter what vehicle you drive you still have to operate it within its capabilities.

RE: car vs tire manufacturers
By talikarni on 5/28/2012 6:18:12 PM , Rating: 2
one problem with that: that only applies to commercial vehicle tires, so that may be true for semi or trailer tires, for most passenger vehicles it will cause under or over inflation.

So based on your calculation, which there is a problem because there is no shown minimum inflation on most tires.

So using mine as example:
Max 44 psi at 2535 lbs., vehicle curb weight of approx 5000 lbs., max load rating of 10140.
We will assume minimum 30 psi.

30 + ((44-30) x .49) = 36.86 psi which is still a shade over 1 psi low instead of recommended 38 psi for these tires (not with trailer load).

When it comes to bias ply tires such as trailer or many semi tires, the ratings are REQUIRED pressure, not "max" or "load" pressure. So if they say 50psi, then fill them to +/- 5% of required pressure. Just make sure the tire load ratings are 10-20% below full load (curb weight).

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