Hoosier product bulletin: P285/30ZR18 Fitments
06-07-2009, 04:35 PM
#1
Le Mans Master
Thread Starter
Hoosier product bulletin: P285/30ZR18 Fitments
Is this old news? The article says this bulletin mainy applies to mid and rear engine vehicles, but I know some of us run on high banked speedways such as Lowes, Daytona etc...
It's worth a quick read imo.
https://www.hoosiertire.com/pbP28518.HTM
It's worth a quick read imo.
https://www.hoosiertire.com/pbP28518.HTM
LAKEVILLE, IN -- There have been some occurrences in which a 285/30ZR18 tire has had sudden air loss. In the cases where the tire remained intact, preliminary analysis has shown that the tire was overloaded or had damaged cords due to impact.
All of the known occurrences have been on rear tire fitments on mid and rear engine vehicles. In 3 situations the track configuration may have contributed to the failures.
Our suggestion, based on these occurrences, is that in high load fitments the P285/30ZR18 be replaced by a tire with a greater load capacity. A rule of thumb to determine relative load carrying capability is the contained air volume. Within common constructions, the greater the contained air volume, the greater the load carrying capacity of a tire.
In cases where the size cannot be changed, it is advisable to increase air pressure to insure a minimum of 40 psi (cold) for unbanked tracks, and 44 psi (cold) for banked courses.
Factors to consider when attempting to evaluate safety margins in the racing environment include: vehicle weight and configuration, horsepower, track configuration, and air temperature. In most cases, high loads will generate higher tire temperatures. Close monitoring of the tire temperatures can provide indications of marginal conditions. Tire temperatures must be taken using the proper technique and equipment to accurately assess the situation. Infrared pyrometers are not accurate methods for race tire applications.
Steps that can increase the margin for durability include: scuffing in a new set of tires, increasing air pressures as recommended, and using wheel widths within the recommended range. Heat cycling does not increase a tire's structural integrity and will not reduce the chance of sudden air loss if a tire is subjected to the conditions described above.
The P285/30ZR18 has proven to be a successful and safe product. In racing there are always possibilities that damage or abuse can exceed the safety margins. With respect to ultra low profile tires, the contained air volume is relatively small. In these cases, a small amount of air loss can dramatically affect the loading on the tire. For this reason it is extremely important to verify and maintain proper pressure settings in the tires. Small leaks from punctures during an event can lead to sudden failures if caution is not exercised.
Another area of concern with respect to ultra low profile tires is their sensitivity to impact damage to the sidewall/tread junction. Because of the small amount of sidewall flex available, it is much easier to damage the casing of these tires when driving over road hazards and curbs. Teams are encouraged to carefully inspect their tires for damage after each run, but it should be noted that some types of impact damage may not be visible to outside inspection. It must remain the drivers responsibility to report incidents of off track driving or banging into a curb to allow the crew the best chance to discover any irregularities. The best form of protection is to avoid the type of driving that would create such damage.
In racing, the performance expectations may require changes in vehicle setup from track to track. This setup should include the selection of the proper tire size for different conditions.
In every case it is the ultimate responsibility of the racer to determine the suitability of an application or fitment.
All of the known occurrences have been on rear tire fitments on mid and rear engine vehicles. In 3 situations the track configuration may have contributed to the failures.
Our suggestion, based on these occurrences, is that in high load fitments the P285/30ZR18 be replaced by a tire with a greater load capacity. A rule of thumb to determine relative load carrying capability is the contained air volume. Within common constructions, the greater the contained air volume, the greater the load carrying capacity of a tire.
In cases where the size cannot be changed, it is advisable to increase air pressure to insure a minimum of 40 psi (cold) for unbanked tracks, and 44 psi (cold) for banked courses.
Factors to consider when attempting to evaluate safety margins in the racing environment include: vehicle weight and configuration, horsepower, track configuration, and air temperature. In most cases, high loads will generate higher tire temperatures. Close monitoring of the tire temperatures can provide indications of marginal conditions. Tire temperatures must be taken using the proper technique and equipment to accurately assess the situation. Infrared pyrometers are not accurate methods for race tire applications.
Steps that can increase the margin for durability include: scuffing in a new set of tires, increasing air pressures as recommended, and using wheel widths within the recommended range. Heat cycling does not increase a tire's structural integrity and will not reduce the chance of sudden air loss if a tire is subjected to the conditions described above.
The P285/30ZR18 has proven to be a successful and safe product. In racing there are always possibilities that damage or abuse can exceed the safety margins. With respect to ultra low profile tires, the contained air volume is relatively small. In these cases, a small amount of air loss can dramatically affect the loading on the tire. For this reason it is extremely important to verify and maintain proper pressure settings in the tires. Small leaks from punctures during an event can lead to sudden failures if caution is not exercised.
Another area of concern with respect to ultra low profile tires is their sensitivity to impact damage to the sidewall/tread junction. Because of the small amount of sidewall flex available, it is much easier to damage the casing of these tires when driving over road hazards and curbs. Teams are encouraged to carefully inspect their tires for damage after each run, but it should be noted that some types of impact damage may not be visible to outside inspection. It must remain the drivers responsibility to report incidents of off track driving or banging into a curb to allow the crew the best chance to discover any irregularities. The best form of protection is to avoid the type of driving that would create such damage.
In racing, the performance expectations may require changes in vehicle setup from track to track. This setup should include the selection of the proper tire size for different conditions.
In every case it is the ultimate responsibility of the racer to determine the suitability of an application or fitment.
