TIRE CLINIC
from the May/June 2006 issue of Today's Tire Industry |
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Q:
We are having problems with bias ply retreading. We have a finished tread radius that is much rounder than it should be. What could cause this?
A:
The most likely cause is low inflation pressure during the buffing process. If the rim or flanges on the buffer are leaking and the pressure drops, the buffing rasp will flatten the tread area during the buff and give the impression that the buff is flatter than it really is. If you inflate the tire to 30 PSI after buffing, it should be the same radius as the buffing template on the buffer. Do not trust the pressure gauge on the buffer, because it will only give you the supply pressure and not the actual pressure inside the tire.
Q: With the major increase we have seen in natural gas prices, is there a possibility that we could reduce our cost with electric heat?
A: It would depend on the rates for gas and electric at your location. I know several people who have switched their household gas to electric and saved money. I have seen very few large electric steam boilers, but I think it is something you should investigate. Gas prices will almost always increase faster than electric rates, but electric rates are still on the rise.
Q: We are seeing a lot less bead damage on casings we receive for retreading. What do you contribute this to?
A: I have noticed the same thing and there are several reasons. There has been a continuing improvement in tire changing tools in recent years and tire service personnel are receiving much better training thanks to a very successful training program developed by TIA. Also, I think fleets are more aware of the costs of bead damage, so they are selecting service based more on quality.
Q: You stated recently that a retreader or dealer should not consider retreading questionable casings during a casing supply shortage. We have several customers who use some of their retreads on slower moving, lighter load vehicles. Why would it be a problem to use the so called “questionable” casings on these trucks?
A: It may not be a problem if the tires remain on this type of vehicle, but in a lot of cases these tires seem to find their way onto a heavily loaded, long haul, high speed truck. And if these tires fail and cause an accident, it will do little good to try to explain that they were not supposed to be on that particular truck.
Q: What are the advantages of a convex rasp hub when compared to a flat rasp hub?
A: The main advantage is the ability to obtain a very flat buffed radius on a circumferential buffer using a 3" or 4" wide buffing rasp. For example, if you were using a normal, flat rasp hub and wanted to accomplish a 28" buffed radius on a 10" wide tread, the rasp head would have to be approximately 13" wide. It is also claimed that the convex rasps run cooler, and while I have not checked the temperature, it makes sense because of less contact with the buffed surface.
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Today’s Tire Industry
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