There was no question changes were needed in the Cup Series, which has seen the introduction this season of the Next Generation car which features an 18-inch bead diameter tire (they were previously 15 inches).<br>But Goodyear has gone further, changing to a radial tire this year instead of bias ply, which was used last season in the first Cup Series dirt race since 1970.<br>Bias ply tires are ...<a class='more' href='https://www.motorsport.com/nascar-cup/news/nascar-bristol-dirt-tire-change/9900982/?utm_source=RSS&utm_medium=referral&utm_campaign=R SS-NASCAR&utm_term=News&utm_content=www'>Keep reading</a>

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