TIRE CLINIC
from the September/October 2006 issue of Today's Tire Industry |
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Q:
Do large earthmover tires have a speed rating marked on the tire?
A:
Most large earthmover tires do not have a speed or symbol on the sidewall, but the manufacturers have charts that recommend maximum speeds based on the load to be carried and the speed and distance the tire will travel. This is referred to as the Ton Mile Per Hour rating or TMPH.
Q: When adhesion pull tests are conducted on truck retreads, what is the recommended minimum adhesion?
A: As far as I know there has never been a minimum acceptable adhesive value established. In most cases in the past, one hundred pounds plus pull has been acceptable, but it is very important to analyze how the separation occurs during the pull test. A tread that pulls free of the bonding surface without tearing into the casing or tread compound is considered to be a possible problem even if the adhesion pull is high.
Q: Can damaged tubeless tire liners be repaired with chemical compounds using no heat?
A: Yes, there are several chemical compounds that can be used to repair tubeless tire liners. Check with your repair materials supplier.
Q: We have been told that we should not use liquid rubber buff on any bonding surface. Is this correct?
A: Yes. Liquid buff should only be used to clean the bonding surface area before it is buffed with a rasp. The liquid buff should never be applied to the buffed surface as it may degrade the surface and cause a loss of adhesion.
Q: We have heard a lot about the new federal standard that replaced the
109 standard. What are the major differences between the old standard and the new one?
A: Federal Motor Vehicle Safety Standard (FMVSS) #139 is a new safety standard that replaces FMVSS #109, and it applies to new passenger and light truck tires. The new #139 standard has brought about a lot of changes and some of those changes will continue for several years. One of the major changes are that all passenger and light trucks (with the exception of MS designs) will be tested on a 1.7-meter road wheel at 75 miles per hour. The MS tires will be tested at 68 MPH. Another major change that is controversial in the tire industry is the new endurance test. This test runs on the same 1.7-meter wheel at the same speeds for a total of 34 hours with the last 24 hours at 100% load. The inflation pressure during the endurance test ranges from 26.1 to 31.9 on passenger tires and 37.7 to 59.5 on light truck. This is well below the manufacturer’s recommended pressure for these tires.
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Today’s Tire Industry
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