Gregory, I have yet to get anywhere near those mileage claims on any tires over the past 50 years. A harder rubber compound will increase the advertised tread life, but grip on wet surfaces will suffer. Plus, harder tires produce a noisy ride in my experience. Compare the Treadwear, Traction and Temperature ratings when buying tires.

Be sure to use either genuine MB coolant or Zerex G-05 when you replace coolant.

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Fred Hoelzle