I do think a 215 mm tire will fit a 6" wide wheel. The 5ksq sitting next to the CQ is running 215/70-15 on stock 15x6 rims. that's a +9% error on the speedo. [(215mm x 0.7 x 2) / 25.4] + 15 = 26.850" [(205mm x 0.6 x 2) / 25.4] + 15 = 24.685" [(215mm x 0.55 x 2) / 25.4] + 15 = 24.311" % error = [(delta A) / A] x 100 Respectfully, -Eric Ferguson