Quote:
Originally Posted by oil pan 4
Most of us on here already know you are going to get better milage with warn out tires. The rubber hardens over time, they weigh less and have better aero due to lack of tread.
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This is not a sure thing to expect as tires age.
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Change in Rolling Resistance Versus Tire Wear
The rolling resistance of each tire was measured using the ISO 28580 test procedure. All tires were measured prior to beginning the testing. At the severe wear condition, the tires were also measured after 400 miles and at the end of the 800-mile test. At the mild wear condition, the tires were measured at the end of the 800-mile test. Tires were also weighed prior to the rolling resistance test and after 400 and 800 miles of wear. The data is shown in Appendix 3. Figure 47 shows the rolling resistance versus the weight of the tires. Some tires, such as type G12 and B11, seem to show consistent decreases in rolling resistance with tread loss, and there seems to be a tendency for lighter tires to have lower rolling resistance.
However, many tires show no clear relationship between tread loss and rolling resistance for this testing."
http://www.nhtsa.gov/DOT/NHTSA/NVS/V...res/811154.pdf