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When are Tires unsafe
The story below is making wonder if the BF Goodrich Trail tires I got as OEM with my 2000 Tundra, with only 26000 miles on them, should be replaced. The center of the tread is good but the edges have lost almost all of the outside cleats that were on them when new. I also notice if I go up steep switch backs that are wet, or the least bit sandy I lose traction even when going slow in two wheel drive. Doing a 360 in a Tundra with the family is not an image I welcome, or am I over reacting to the story below:
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My father in law got into an accident on the interstate recently in the rain on the way to my house. He hydroplaned and lost conrtol of the car at 65 mph the car did a 360 and went up an embankment hit some object with the right front fender. Blew a rear tire when he hit a curb. Spun some more and wound up in the middle lane of three facing the wrong way sideways, with cars coming at him at 70 -80 mph in the rain. He managed to start the car and get to the side of the road where he changed the flat tire.
He got to my house and when I looked at the tires on his car you could see that they had 30k miles on them and that while the tread was not bad in the middle the edges of the tires were worn somewhat.
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Dennis
Tractorpoint
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When are Tires unsafe
Dennis,
It sounds like the tires in both cases are or have been underinflated. If both edges (not just one edge which may be caused by fast cornering or improper alignment) wear before the center, this can indicate underinflation.
Anyway, I would think you should get new tires. I bet if you drove the tires you have now back-to-back with how they were when new, you would say they were dangerous. But because you drive it every day, the effect of the worn tires sneaks up on you.
I usually wait too long for new ones. When I get them, I can't believe how much they help handling and traction. Have learned the same lesson over and over.
Bill
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When are Tires unsafe
When a tire has reasonably good tread in the center but is almost bald on both shoulders it is almost certainly a sign of under-inflation for the load it is carrying.
A lot of misconception surrounds tire pressures.
The best rule of thumb is to run the size & type of tires, at the pressures recommended, that are listed in the owner's manual & also shown on the sticker in the driver's door jamb.
If your tires are worn in that manner it is best to replace them, that is not to say they are defective in any way, they are just worn, and most likely from incorrect tire pressures.
Best of luck.
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When are Tires unsafe
I agree with the diagnosis of underinflation.
Safety depends on how and where you drive to some regard, but since you do not have absolute control over your driving environment and conditions, it is generally best to keep your tires and vehicle in top shape. It would certainly seem foolish to have a wreck to save a couple hundred bucks on tires.
With respect to inflation, I would recommend that you monitor the tread wear and adjust the inflation to the amount that gives you a more even wear. It is normal for front tires to wear on the edges a little more due to steering forces. (That is why you rotate them) But, it sounds like you have significant edge wear and higher air pressure will carry more of the load in the center of the tires.
Some of the recent press about tires deals with tread separation, which is a different safety problem.
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When are Tires unsafe
Assuming even wear the tires must be replaced when 2/32" of tread remains. That is when the tread-wear bars start to appear horizontally across the tread.
Here in rainy western Oregon I replace our tires when they wear to 4/32". Hydroplaning is nasty business and your tread has to have sufficient depth to allow water to drain away. In a dryer climate I may go to 3/32", but I think 2/32" is unsafe in any climate. If the edges are worn enough to prevent water from draining out the sides of your tires hydroplaning risk increases a lot.
The classic explanation for tires wearing on the edges is underinflation. That sure can cause it, but there are other reasons. It could it caused by poor wheel alignment, weak shocks, mechanical problems in the front end, and even suspension design or tire construction. If the wear is sort of scalloped or cupped (not smoothly worn around the circumference of the tire) I would lean toward out-of-balance, weak shocks, or front-end problems.
If both inner and outer edges are worn smoothly around the circumference it would probably be underinflation. If the inner and outer edges are wearing differently it would generally be caused by alignment problems or suspension design. The old Ford I-Beam comes to mind - those suspensions would chew up tires like nobodys business. Vehicles with short control arms tend to wear edges faster than those with longer control arms.
And sometimes some brands just wear faster than others, and sometimes they do it in odd ways. New tires generally have anywhere from 9 to 13/32" of tread on them. Obviously the thicker the tread when new the longer they will last. Thick tread has a downside in that those tires tend to be a bit noisier and sing more at highway speeds. For this reason (and cost of course) manufacturers often put tires with lesser tread depth on new vehicles.
A tread depth gauge is a cheap item to have, and it's good to go out and measure your tread every couple of months to see if the tread is wearing evenly. You can catch problems early this way and save some bucks.
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When are Tires unsafe
Yup the tires are worn on both edges so it is underinflation, plus just plain old wear.
I usually set the pressure to be 2 pounds higher than the vehicle recommendation, but the recommended pressure is only 26 front and 29 year which seems low to me.
I took some pix of the tires in my frames 7 and 8 , 8 is my original spare, hmmmm what do you think, pretty shot?
They look worse now with the comparison.
Of course the treads on pix 6 look much better that 7 or 8 ;>)
I rotate the tires, and the wheel alignment is OK so I think is just the combination of.
1)Bf Goodrich are not long wearing tires
2)Toyota set the inflationpressure low to give a smooth ride
3)Off road tires wear faster
4) 4wd causes more corner wear
I will probably replace these with michelins, I had them on a Jeep Grand Cherokee and they still looked good with 64000 while the original goodyear wranglers were wasted at 30k
Dennis
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When are Tires unsafe
It's easy for me to spend your money, but yes I would recommend replacement. People may throw stones at me for saying this, but I generally ignore the manufacturer tire pressure recommendations. If I am unsure about which pressure is best for any particular application I start with the maximum sidewall pressure. If the ride causes the fillings to fall out or your teeth you can back it off some, but keep it high. As you drive use a treadwear gauge every month or two to make sure they're wearing evenly. If they wear too much in the middle you can back off the pressure a few lbs, or if they wear too much on the edges you should bump it up even more.
As you indicated, manufacturers often specify a low tire pressure to give a smooth ride but that doesn't maximize tread life. I believe one factor in the Ford/Firestone Explorer tire fiasco was that Ford had specified too low a pressure. Low pressures increase heat build-up which leads to tread separation.
BTW, Michelin makes a fine tire but I discovered from my years in the tire shop that they seem to use less rubber per tire than nearly any other manufacturer. The inner liner of their tires is VERY thin - you need to be very careful when patching a michelin from the inside. This sounds bad, but less mass means cooler running and excess heat really shortens the life of a tire. For my money, though, on any vehicle which is going to see a hard off-road life or spend a lot of time on gravel roads I'd rather have MASS.
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When are Tires unsafe
I have owned many sets of Bridgestone Desert Duelers. They make a variety of treads, and I personally use the AT tread which is the most open and agressive. I had one set on a truck that had gone over the Baja 1000 course several times. I was very pleased with their life and performance.
I run the Bridgestones at near maximum pressure as stated on the sidewall, as Ken suggests. I lower the pressure only when I am going offroad and want more floatation and to keep the punctures down. I have only had two or three punctures in several years of running these tires. I would say that I get >60K miles out of a set of these and they don't stay on the pavement.
I am sure that others can relate stories about other brands. I was bothered when Ford was having trouble with Bridgestone/Firestone, but I tend to believe that the fault was with Ford and underinflation.
My wife had a set of Toyo tires on her truck and they lasted even longer than the Bridgestones. I have never used Michelins on a SUV. I replaced OEM Goodyears and BF Goodrich tires with Bridgestones, but it may be that replacement tires are higher quality than those sold as OEM. (Even within the same brand.) My Hummer has some huge BF Goodrich TA tires that seem to be doing well.
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When are Tires unsafe
Ken,
It is interesting how pieces of knowledge can come together, I have never worked at a tire dealership so I did not know that Michelins were thinner and cooler running.
Now let's add this to the mix. From 1995 to 1999 I worked for the Engineered Materials Division of Alled Signal (now Honeywell).
In 1996 I went on a business trip to Europe for Allied Signal. We visited a polymers plant that Allied had completed 2 years before my visit. The plant cost a fortune, it was huge. The purpose of the plant was to supply tire cord solely to Michelin Tire. Because of this the plant was built in an obscure area of France close to one of Michelin largest plants.
Our Allied tour guide pointed out that while the objective was to supply tire cord to Michelin, the plant while brand new and state of the art for Allied, was never able to manufacture tire cord that was #1 grade, this was an enormous failure for Allied and millions and millions were lost because of it.
The polymer cord grading had to do with cord strength / consistency if I recall correctly. Michelin only purchased first quality cord and therfore never bought any cord from Allied. Therefore they wound up having to ship it longer distances than hoped for to other tire manufacturers who had lower standards at the time.
So maybe the thinner carcas on the Michelin has something to do with higher spec that they follow.
Dennis
Tractorpoint
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When are Tires unsafe
Dennis,
that's quite interesting. I know Michelin makes a top-notch tire for the road but I'm not sure how good they are for off road or gravel road situations. We didn't see a lot of those applications at our shop. The guys who bought the big and beefy off-road tires never seemed to actually go off road.
It's really a matter of picking the right tire for the job, and avoiding marketing hype. For example, I really like to see a cross section of the tire I am purchasing. Why? Well in the 80's Goodyear sold a Polysteel steel belted radial. They sold quite well but seemed to have a lot of road hazard failures. One slow day we cut one open and found that the steel belt was about 2" wide covering the very center of the tread. The tire footprint was about 9-10" and only 20% of it was protected by the steel belt!
More plies is better for impact resistance and load carrying, but 8/10/12-ply tires will wear out faster at highway speeds than a 4 ply or 4 ply rated tire due to the extra heat. Nylon cord is the strongest and stretches the least but for passenger cars it is rough riding when cold (they take on a flat spot when sitting overnight and it doesn't go away until they warm up) so polyester is popular among passenger car tires.
We have to drive up a 5 mile rough gravel logging road to get to our house. When I tire shop I look for strength, traction, and impact resistance (nylon and steel belts rule!) and let the tire-wear chips fall where they may. I really hate changing tires on a narrow gravel road with logging trucks barreling by at breakneck speeds.
If I were still in the business it would be interesting to use one of those point-and-shoot infrared thermometers to measure tire temps as people drive in. I'm sure you could tell a lot about tire construction, alignment, and inflation by measuring at several points across the tread. That's how the racing guys do it.
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