Which tire has the highest Treadwear (UTQG) in size 305/45R20

It's time to buy new tires for my car, but I want to buy a tire that lasts longer than the original brand, OEM. Which tire has the highest Treadwear in this size 305/45R20?

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500 - Treadwear

 Yokohama Geolandar A/T-S G012 - UTQG: 500AB - Tire Rating: 4.52

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420 - Treadwear

 Kumho Ecsta STX KL12 - UTQG: 420AA - Tire Rating: 4.5

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320 - Treadwear

 Yokohama Advan ST - UTQG: 320AAA - Tire Rating: 4.55

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