I'm assuming you're keeping the same aspect ratio, then going to 245/50 gives you a speedo difference of like 2.9%. You can use any tire size calculator to compare the difference and see. I think most recommend staying within 3% of stock so this is at the upper limit.
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SOLD 12/30/2011 2010 370Z Coupe Monterey Blue 6MT/Touring/Sport/Nav
F.I. CBE CF w/ 12" Res | V1 | SecondSkin | Stillen G3 | EVO-R CF B-Pillars | Volk GT-S Ti Gunmetal 19x9.5 +30 F, 19x10.5 +8 R | Swift Spec-R Springs
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