| Author | Message | ||
| Doug McCartney (204.182.81.207)
Rating: |
I make my living training bus mechanics. The curriculum that I teach includes a tire safety class. There is some very important information that ALL people that operate medium and heavy-duty steel cord radial tires should know. Most likely this type of tire is what you are using on your conversion. IF THE PROPER PRECAUTIONS ARE NOT TAKEN WHEN INFLATING THESE TIRES, THEY CAN EXPLODE AND KILL YOU. Medium and heavy-duty steel cord radial tires differ from passenger and light duty truck tires because the sidewalls are reinforced with steel cords. Passenger car and light duty truck tires usually have nylon or polyester sidewall cord material and do not use steel in the sidewall. If you are not sure of the sidewall construction, it is printed on the side of the tire. Steel is an excellent material for sidewall reinforcement of truck tires. Virtually all quality truck and bus tires are constructed with steel cord sidewalls. The problem comes when the tires are under inflated (operated 80% or less of the recommended pressure) or overload. If the tires are operated under these conditions the sidewalls flex excessively, weakening the steel cords. Similar to bending a steel coat hanger back and forth until it breaks. When the damaged tire is inflated the sidewall can rip out causing injury or death to anyone near it. The tire industry refers to this type of sidewall failure as a “ZIPPER RUPTURE”. The damage cannot always be detected visually. Even breaking down the tire and visually inspecting the tire will not always show evidence of the damage. Another disturbing fact is that the damaged tire can fail at any time but most often occurs during inflation. Tire professionals have the tools and expertise to deal with these problems. DO NOT MESS WITH THESE TIRES!!! Any time that you add air to a steel cord radial truck tire always use a clip on chuck and stand clear of the sidewall of the tire. The International Tire and Rubber Association recommends the following practices for steel cord radial truck tires: All tires with less than 80 percent of the recommended operating pressure are basically flat. Any tire with less than 80 percent of the recommended pressure must be completely deflated BEFORE it is removed from the axle, demounted and thoroughly inspected before it can be returned to service. AND Any tire next to a tire with less than 80 percent of the recommended inflation pressure should be considered suspect because of the overloaded operation. Any tire next to a tire with less than 80 percent of the recommended inflation should also be completely deflated BEFORE it’s removed from the axle, demounted and thoroughly inspected before it can be returned to service. More information can be found at http://www.retread.org/TireRepair/index.cfm/Article/197.htm Taks care and be safe! Doug | ||
| TWO DOGS (65.179.208.153) Rating: N/A |
YA' scared the fat boy.... | ||
| Henry R. Bergman, Jr. (Henryofcj) (63.224.197.10)
Rating: N/A |
I thank you for the important info....however....just speaking to myself, I wonder if it is possible that something as common and proved as a steel cord truck/bus tire.... ....could be so potentially dangerous. Wonder also what the explosion rate is upon failure. I mean....where are all the dead bodies along side all the trucks and buses? Just wondering. I also noticed that the warning comes from the tire makers association and NOT the highway safety board. Seems to me if that we had such an apparent problem with ALL our tires.... ....we would have heard about this from another source. Are other agencies crying out also? I do not know that either. And yeah...you scared this here old boy too. Thanks. | ||
| Doug McCartney (204.182.81.207)
Rating: N/A |
Hi Henry, This problem is not a defect in the tire. The problem does not happen often, but when it does it can result in a death. That is why it is important. People that have these tires on recreational vehicles are especially vulnerable because they often are not trained or experienced in dealing with steel cord radial truck tires. OSHA 1910.77 contains special requirements for handling truck tires that are designed to prevent injury to those that service tires. Employers are required, by this act, to train their employees on the correct procedures. Tire professionals know the dangers associated with servicing these tires and are quite capable of handling them in a safe manor. The tires are not dangerous if handled properly. The problem is that the average recreational vehicle owner is not even aware of the danger of improperly handling these tires. Most folks that had a low tire on their coach would simply fill it up without giving it a second thought, not knowing the danger that they are placing themselves in. If you treat your bus tires like you treat your passenger car tire you are putting yourself at great risk. I am aware that the “average Joe” has never heard of this. That is mostly because the average guy never has to deal with commercial truck tires. The professionals are aware of the dangers. They know and follow the proper procedures. Motorhome and bus owners are often unaware of the dangers. I am posting this information here to inform you of the dangers, in hopes that it may prevent someone from getting injured or killed. Take care, Doug | ||
| Bill Butler (67.75.227.194)
Rating: N/A |
Thanks Doug. I have known for years that inflating any tire can be dangerous. Tires as well as some rims have been known to blow-up. Always use a clip-on inflator. I carry 110 lbs in mine and that is where my compressor blows its top so when it blows I quit. | ||
| Buswarrior (Buswarrior) (64.229.210.226)
Rating: N/A |
I'll throw my support in for Doug. He has faithfully reproduced the heavy tire safety gospel with regard to underinflation and the risk of zipper failures. Our transit fleet is quite religious about inflating newly mounted tires in tire cages with clip on air chucks. An in-service tire found below 80% of it's proper pressure is deflated and removed for demounting and inspection. We've had a couple of instances of inside dual tires failing, blow through the wheel wells and into the passenger compartment, bringing a chunk of 3/4 plywood flooring with it. The training movies showing the blast effects of a zipper failure are a real eye opener. If you are beside it when it let goes, the absolute minimum will be hearing damage, worst case will be death. That ain't your father's Oldsmobile tire.... happy coaching! buswarrior | ||
| ChuckMC9 (Chucks) (66.167.165.85)
Rating: N/A |
All tires with less than 80 percent of the recommended operating pressure are basically flat. Any tire with less than 80 percent of the recommended pressure must be completely deflated BEFORE it is removed from the axle, demounted and thoroughly inspected before it can be returned to service. Doug, what if I discovered a tag tire that went flat only because the valve stem was leaking, with no loading and no driving on the tire? And being a tag, it never sagged with any significant weight on it. Will be re-inflating with an clip-on. Should I be worried about the sidewalls? | ||
| dougmac (204.182.81.207)
Rating: N/A |
Chuck, If the tire has NOT been driven on, the sidewall should be fine. To be safe, be sure that you are clear of the sidewall while you are inflating it. If the tire has been run low at some time in it’s life it could fail when you inflate it. Take Care Doug | ||
| Peter Broadribb (Madbrit) (67.136.216.54)
Rating: N/A |
If the tire is uninflated or very underinflated, I would treat it as a new instal and place it in a cage. Peter. | ||
| Randall Hays (69.4.195.98)
Rating: N/A |
Hello all, I had a zipper failure about 2 years ago when unknowingly I had a tire loose air and I was lucky in that I was bent over trying to hold the airchuck in place and the inside tire blew out. It took out the side pannel of the motor home and scared me half to death, missed my head by inches. I use the locking chuck now and I also check my tires each time I am parked in an unfamilure place before I leave not only because I should but also just to make sure some kid didn't come along and "have some fun". I also check them before I go on a trip. Also as a note, I use the new digital gauge which is more accurate than any other. | ||
| Ron Walker (Prevost82) (209.52.245.237)
Rating: N/A |
Up here in the north country, interior of BC, we have a lot of logging trucks running CTI(central tire inflation) system. They reduce the tire air pressure by 50% (60 PSI)with a 54500 kg load, 6 axles, on gravel logging roads with speeds up to 80 km/h (50 mp/h) max. This increases their traction and reduces the impact on the road surface...so they can haul longer without breaking up the road in the spring. All test have shown that there is no sidewall damage to the tires with these loads and speed. When they hit the pavement they hit a switch and the tires are filled back up to full pressure and they can run at highway speed. Ron |
