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  • We occasionally section repair radial wide-based tires that could wind up on the steer axle of a local delivery truck, such as a dump truck or a waste hauler truck. We think our repairs are done very well, but would you do a section repair in a tire for steer axle use?"
    I would not put a tire on the steer axle of a truck if it had been section repaired. The reason is not because I think the repair would not hold up, but if the tire was to have any kind of failure, and the vehicle was involved in an accident, the blame would fall on the repaired tire - even if it had been run flat - because someone shot a hole in it. It would not matter why the tire failed, the blame would be placed on the section repair.
  • We are finding a small-molded triangle at the end of the date code marking on some of the casings we receive for retreading. It only shows up on some of the casings with a three-number date code and never on the ones with a four-number date code.
    This triangle means the tire was manufactured in the 90's. At that time, having the triangle was not required, so you will find some tires manufactured in the 90's that do not have the triangle. Since all tires manufactured today are required to have a four-number date code, the triangle is no longer used.
  • Can I move my retread plant to a different location and keep my same DOT plant code?
    Yes, you can. Just send a letter to Jeanette Greenfield, Office of Vehicle Safety Compliance, 400 7th St. S.W., NSA32, Washington, D.C. 20590, and give your new address and current DOT code.
  • I recently read that NHTSA has released a new report on new and retreaded truck tires. It is over 200 pages, and I have not had the time to read it. Is it good news or bad news?"
    The NHTSA report that was released in January 2009 basically presents information regarding retread performance that has been available for years. Most of the information comes from a study conducted by the University of Michigan that confirms that most rubber on the road is the result of poor tire maintenance; not retreaded tires.
  • What are the advantages and disadvantages of widebase tires and traditional duals?
    There are four factors to consider: fuel economy, weight, availability, and tread life. Here's how each stacks up: Fuel economy: Compared to standard compound tires on steel wheels, widebase tires on aluminum rims would probably offer a fuel economy advantage. Compared to tires with "fuel efficient" tread compounds on aluminum rims, the wide base tires may offer little or no measurable advantage. Increased revenue: A vehicle that reaches its weight limit before reaching its cubic capacity limit can benefit from the fact that four wide base tires on aluminum wheels weigh less than eight conventional tires on steel rims. The reduced vehicle weight means more cargo weight can be carried. Most interest in these tires has come from bulk haulers. Mixed-service applications have been the slowest to adapt since durability and retreadability issues are so vital to their operation.
  • Why should I check the lug nuts 50-100 miles after the wheels have been installed?
    When dual wheels are installed the bolted joint that encompasses the stud, hub/drum, wheels, and fastener is going to flex as soon as the axle is loaded. The initial flexing results in joint settling that can cause the wheels to become loose. By checking the lug nuts after the first 50-100 miles of service, any joint settling that has occurred can be corrected by tightening or replacing the fasteners.
  • Why should I pay extra to properly repair a flat tire when plugging is so much cheaper?
    Unless you have xray vision any damage on the inside of the tire cannot be detected when plugging the tire on the rim. By removing the tire from the rim, inspecting the interior, and repairing the damage with a rubber stem and a repair unit, the integrity of the tire can be restored or potential problems can be identified. Proper tire repair also protects the casing so the tire can either be retreaded or returned for credit.
  • Is it legal to repair a steer tire?
    A steer axle tire with a puncture repair in the crown area that is 3/8" or less in diameter can be repaired using a rubber stem and a repair unit. If the injury is larger than that or in the shoulder or sidewall the tire can be repaired with a section repair but it cannot be returned to the steer axle.
  • I run fully loaded but come home empty. What can I do to reduce irregular wear?
    You can reduce your tire air pressure based on the load/inflation charts, however you must be very careful to increase the air pressure when you are running loaded. Most fleets feel that this is an unsatisfactory and not a practical solution since it leaves the door open to low tire pressure if you forget to reinflate. Unfortunately, there is no other way to reduce uneven wear in this scenario.
  • Should my air pressure be what's listed on the sidewall?
    The air pressure listed on the sidewall is the recommended air pressure for the maximum tire load. The maximum tire load is also lsited on the sidewall. To be safe, most drivers will inflate their tire to this level. But, if you want to get the maximum life out of your tire and you know your actual tire load, then there are load/inflation charts which can help you determine recommended tire air pressure. A good online reference chart can be found at: Click on tire information to download an inflation chart.
  • Why are there speed ratings on some medium and heavy-duty truck tires and not on others?
    Tires that may be used in Europe will generally have a speed rating or symbol. In the United States, with a few exceptions, the only truck tire with maximum speed ratings posted on the casing will be local use tires, such as tires for dump trucks, concrete mixers, etc.
  • Once the tread design is worn off the radial truck tire casing with a maximum 55 mph rating, is it legal to operate it at a higher speed after it has been retreaded with light, high speed tread designs?"
    I do not know of any law that addresses this, but it is not a good idea. The heavy-duty casing would likely become overheated and fail, if driven at high speeds.
  • Is there a federal law regulating the minimum allowable tread depth for truck tires?
    Yes, the federal law on minimum tread depth for truck tires is 4/32 inch on front axles and 2/32 inch on other wheel positions.
  • Is there any situation where plugging a hole in a tire and not using a patch would be an acceptable industry practice?
    Not according to tire manufacturers. Using a plug without a patch is a common practice for repairing tires that are not used on public roads because repairing a tire on a lawnmower, slow moving farm tractor, and similar types of equipment appears to present little risk. With that in mind, I would still recommend that the tire be removed from the rim and inspected before repairing for the safety of the tire technicians.
  • When would it be acceptable to inflate a tire to the maximum pressure?
    With truck tires this is a common practice because of the heavy loads they carry and the fact that most heavy-duty trucks do not have a placard in the vehicle that recommends a specific inflation pressure. The tire manufacturers and the tire and rim associations have a chart that recommends the correct inflation pressure for the weight that the tire is carrying. The inflation pressure for passenger tires is designated on a placard or owners manual in each vehicle.
  • Is there a federal regulation requiring trucks to use new tires when hauling toxic waste?
    No. There are no federal regulations that require new tires to be used on any truck.
  • We are new to the retread business in our country and we wish to know how old a tire can be and still be retreaded or repaired.
    There is no simple answer to you question, as in most cases a tire is rejected for retreading or repairing not because of its age, but because of its condition. Many tires may be unacceptable for retreading when they are only a year old, while others may be perfectly acceptable for retreading when they are close to ten years old. It all depends on how well the tire is maintained and how and where the tire is used. Some environmental and operating conditions can destroy even the best new tires very quickly.
  • Do I have to remove any information from a truck casing before it is retreaded?
  • How do I go about getting a DOT Code for a new retread plant we are opening?
    Contact Janet Greenfield of the DOT at (202) 366-5317.
  • Does the DOT Code on retreaded truck tires have to be molded on the tire sidewall or can it be branded into the sidewall?
    It is a very common practice to brand the DOT Code on retreaded tire sidewalls. Make sure you don't brand too deep and the brand should be as close to the bead as possible. It is also a good idea to place the brand near the original DOT or any other DOT retread codes.
  • We recently purchased a retread plant. Do we have to apply for a new Department of Transportation (DOT)code, or can we use our old one?"
    The DOT may allow you to use the same code, but you must notify it of any change in company ownership or address. Contact the United States DOT at 202/366-4000.
  • How will 20 percent overinflation in a steel radial truck tire affect the tire's performance?
    It depends on how the tire is used and the surface it is used on. If the tire runs on a smooth surface, it will likely develop some irregular wear. If it runs on gravel or travels over rough surfaces, the tire will likely experience severe cutting, chipping and other impact damage. Wet gravel makes the cutting and chipping worse. We recommend using only the inflated pressure required for the speed and load.
  • Do you recommend destroying a casing that may be dangerous to mount and inflate, even if it belongs to your customer?"
    We think it is a good idea, but your customer may not agree. It is the customer's property, so get his or her permission before destroying a casing.
  • We mark our truck retreads with "R-DOT" designation along with our additional company information and the date. We just learned that we should not put the DOT symbol on our tires. Is this correct?"
    The "DOT" symbol is for use on passenger retreads. Truck tire retreads should be marked with the "R" symbol only. The Department of Transportation regulates only passenger retreads.
  • I understand that the maximum allowable injury for a nail hole repair in a large radial truck tire is 3/8"(10mm), but I don't understand why a 3/8"(10mm) injury in the sidewall requires a more costly section repair. Please explain."
    The tread area of a medium radial truck tire features four to five layers of steel cord-three to four belt plies and one body ply-while the sidewall has only one steel body ply. Given those features, the tread area is heavily reinforced so that the repair unit for a 3/8"(10mm) puncture really only has to seal the injury. The sidewall offers much less reinforcement and flexes more than the tread, so it calls for the extra support of the larger unit required of a section repair.
  • Is it true that any irregular tread wear pattern that develops in an original new tire will show up again when the casing is retreaded?
    An irregular tread wear pattern is usually caused by operating conditions, the tread design, or poor maintenance of the tire or vehicle. The tire casing has very little effect on tread pattern wear.
  • I was told that I should not mark my truck retreads with the DOT symbol, but instead should use the "R" to designate "Retread". Is this true, and why?"
    In your case, the "R" designating "Retread" (along with the additional required identifying information) is sufficient because there are no standards for retreading truck tires. On the other hand, there are standards for passenger retreading that require the DOT code and "R" (along with the additional identifying information)Contact TIA at 800/426-8835 for a copy of the DOT Part 574-Tire Identification & Recordkeeping requirements.
  • We perform free air pressure checks for truck drivers on a regular basis. We know that any tire with less than 80% of the recommended inflation pressure must be deflated, demounted and inspected before it can be returned to service. What do we do when a hot tire is underinflated but above the 80% threshold?"
    According to the Rubber Manufacturers Association/RMA, underinflated hot tires above the 80% threshold should be inflated to the cold inflation pressure plus 10psi. Once the tire cools to atmospheric temperature, the inflation pressure can be adjusted to the correct level.
  • How long does a truck have to sit before the cold inflation pressure can be read?
    Generally, the cold inflation pressure can be recorded after the vehicle has been parked for at least 3 hours.
  • We know that temperature changes have a direct effect on inflation pressures. What about altitude?
    For every 1,000-foot increase in altitude, there's a 0.5 psi increase in inflation pressure. So a tire that starts in Denver inflated to 100 psi will read around 97 psi at sea level and a tire inflated to 100 psi at sea level will read around 103 psi in Denver. In other words, it doesn't have much of an effect.
  • We know the minimum tread depth allowed on steer axle truck tires is 4/32" and the minimum for drive axles is 2/32". What is the minimum tread depth allowed on lift axle tires?"
    The answer is 2/32". The regulation (393.75 (c)) doesn't specifically mention lift axles, but it states that all tires other than steer axle tires must have 2/32" tread remaining.
  • How many repairs are acceptable in a standard tubeless radial truck tire?
    The number of repairs is unlimited, as long as the repair units do not overlap, and the same radial body cable is not injured more than once.
  • I am aware of some new truck tires that have been imported into the United States without a production date code. Can these tires be sold in this country? They have an ISO 9002 marking, the letters "DOT" and a two-letter manufacturing plant designation."
    The Department of Transportation (DOT) states that any tire without a production date code and the complete DOT marking requirements cannot be sold in the United States. The ISO 9002 designation does not require testing of the tire and is not a substitute for the DOT code marking.
  • At what point will a truck tire burst from overinflation?
    Most new or undamaged medium radial truck tires can withstand three to four times the recommended pressure before bursting. In fact, the rim usually fails before the tire. ITRA has conducted several burst strength tests on new and used medium radial truck tires with special reinforced rims. The tires were pressurized with water. Most recently, three new tires and 13 used tires were "burst tested" with the lowest pressure burst recorded at 300psi and highest at 540psi for an average of 420psi. All of the test tires failed in the bead area.
  • How do I know if my tires are suitable for retreading?
    Only your retreader can make that determination after your tires have been inspected in the retread plant. Tires that have been run underinflated or have been pulled with less than 4/32" of tread left are more likely to be rejected than tires that have been properly maintained and pulled with 5/32" or more tread remaining. This is, of course, a good argument for properly maintaining tires. Before the retread process begins all tires are subjected to both a visual inspection and an inspection on a non-destructive testing machine (there are several equally good systems now in use). Only those tires that pass this stringent inspection are allowed to continue through the retread process.
  • How many times can a steel radial truck tire be retreaded?
    That depends on the condition of the tire and how much damage it has accumulated. Long haul, high-speed operations usually retread their tires two or three times. While fleets, such as garbage hauler and other local service operations that wear tires out very quickly, can sometimes retread their tires five or more times if they are properly maintained.
  • Which are affected more by underinflation, radial or bias truck tires?"
    The extent of underinflation and the speed and distance the tire ran are factors to consider. Also, underinflation affects tubeless and tube-type tires differently. In fact, it causes so many conditions we think it best to state that underinflation causes damage to all tires and should be avoided. We do not recommend any tire as being better than another when run underinflated.
  • What are the regulations regarding the use of retreads on steering axles?
    This is an issue that confuses many people. A misconception exists that retreads are not allowed on the steering axle of any vehicle. The fact is, retreads can be used on the steering axle on any vehicle with the exception of a bus. Paragraph "d" of the Federal Motor Carrier Safety Regulation Title 49 Part 393.75 states, "No bus shall be operated with regrooved, recapped or retreaded tires on the front wheels."
  • Can a company operate multiple retread plants under one Department of Transportation (DOT) shop identification code?
    No. Each physical location must have it's own DOT code.
  • We know that underinflation shortens a tire's life. Does overinflation do the same?
    It depends on the type of tire, vehicle speed, travel distance and the surface it travels on. Overinflation can cause irregular tread wear, poor handling characteristics and severe impact and cut damage, on rough or rocky roads. Check with your vehicle manufacturer and tire supplier for their recommendations for your particular situation.
  • Which surface wears a tire faster, a wet or dry surface?"
    If the tire is free rolling and not slipping, a wet surface lubricates and cools the contact area of the tire, thereby causing it to wear at a slower rate.
  • What is the origin of the word rubber?
    Believe it or not, in 1770 an English chemist named Joseph Priestly created the word "rubber" when he found the material could remove pencil marks from paper.
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