Effects of Aging on Tire Properties

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MSI
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Effects of Aging on Tire Properties

Post by MSI »

Q: Is there any data out there regarding the effects of age on the frictional capabilities of a tire?


A: Saw this posted up on another forum and the following reference was mentioned so we got the reference and present some of the information:
Effect of Aging on Tire Force and Moment Characteristics
Tandy, Pascarella, et al
SAE Paper 2010-01-0772
Abstract
  • There has been very little investigation into the area of tire aging and whether storing a tire will change it's properties, in particular ‘limit’ or ‘saturated’ properties, over time. In order to study how the performance characteristics of tires change when the tires are stored, a series of force and moment tests were performed on five modern day radial tires of different make, brand, type, and size. The tires were all purchased at the same time for a given tire set and had the same DOT code. Near the date of purchase, some of the tires were tested on the Veridian TIRF (Tire Research Facility) machine in order to measure their force and moment characteristics. Other tires of the lot were placed on a tire rack in a storage building. Years later, these tires were sent to the same test facility and were measured under the same test conditions. The data indicates that tire performance characteristics change very little with time. When some change was noted, it tended to show that age causes tires to have a higher cornering stiffness values and similar saturated lateral force capacities.
TIRES
  • The tires used in this experiment were all purchased at the same time and had the same DOT code. Some in the purchased lot were tested over a period of weeks, while others were put into storage in a non-climate-controlled storage facility in Houston, TX. Conditions of storage, though not monitored, are reasonably assumed to have been of moderate temperature and humidity year-round, rarely if ever cold. The tires studied were:
    1. Bridgestone Dueler HT P225/70R16
    2. Bridgestone Dueler HT P235/75R15
    3. Firestone Wilderness AT P255/70R16
    4. Goodyear Wrangler HT LT245/75R16 E
    5. Yokohama Geolander G039 P265/70R16
CONCLUSIONS
  • Based on the above results, several conclusions can be drawn:
    • Consistent with the previous study of [2], cornering stiffness seems to increase with tire age. Since no history of the temperatures the tires experienced while in storage is available, no conclusions could be drawn about the effect of temperature on the magnitude of the rate of increase with age.
    • With respect to peak overturning moment, a strong negative correlation with age was seen, which is hypothesized to be due to the aged tire having a stiffer sidewall and thus deflecting less under load, thereby reducing the moment arm through which vertical tire patch load would act to contribute to the total overturning moment.
    • With respect to maximum saturated lateral force capacity, no absolute trend due to tire aging was found. While the data shows that the majority of tires showed some increase in this capacity with age, there was wide variation in the rates of increase that was greater than the effect of aging itself. Also, a data point did exist where the capacity decreased with age. The primary conclusion to draw is that the effect of aging is small and tire dependent.
RELATED:
  • 2. Pottinger, M.G. and Marshall, K.D., “The Effect of Tire Aging on Force and Moment Properties of Radial Tires,” SAE Technical Paper 810066, 1981.
    • As discussed in the above 2010 paper:
      • "Pottinger and Marshall [2] performed a seminal study that examined the effect of aging on linear range performance, specifically in the +- 1 degree of tire slip angle regime (which for some vehicles may even be at the lower end of the linear range), using the BFGoodrich tire test machine. This study found that tire cornering stiffness increased directly as a function of age and the effect was independent of tire make or size. It was also determined that the rate of change was directly proportional to the temperature conditions under which the tires were stored. An
        additional experiment performed by Pottinger in the same paper found that under conditions of normal driving use on an actual vehicle, the increase in cornering stiffness due to age was not observed. It was reasoned that this finding was due to a cancelling of the tire aging effect by the known effects of tire wear and heating, though this could not be objectively determined."
      • ABSTACT from the 1981 paper
        • The increase of rubber stiffness with age causes radial tire cornering stiffness to significantly increase during warehouse (shelf) aging. The increase in cornering properties is linear with the logarithm of time and dependent on storage temperature. Five different brands of radial tires studied age in a very similar manner, exhibiting the apparent effect of two different aging mechanisms. A limited experiment indicated an approximate balance of aging and break-in effects on radial tire cornering properties in normal service. The in-service results imply that neither force and moment tests nor vehicle handling tests should be preceded by break-in or scrub-in procedures if the desire is to predict in-service behavior.
cornering stiffness change over age.jpg
cornering stiffness change over age.jpg (257.1 KiB) Viewed 5285 times
aging lateral force.jpg
aging lateral force.jpg (36.27 KiB) Viewed 5285 times

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