| ... unless it's to admit you were wrong, at least. I sampled some tires... all 205 width, looking at 45, 50, and 55 aspect ratios. Obtained the following data: 45 7.5
45 7.2
45 7.6
45 7.4
45 7.1
45 6.9
45 6.9
45 7.6
45 7.0
45 6.7
45 7.4
45 6.9
45 8.0
45 8.0
45 7.1
45 7.0
45 6.5
50 7.2
50 7.3
50 7.2
50 6.6
50 6.6
50 7.0
50 7.2
50 7.4
50 6.7
50 7.2
50 6.3
50 6.5
50 7.0
50 7.4
50 7.1
50 6.6
50 7.2
50 6.6
50 8.4
50 6.5
50 6.8
50 7.2
55 7.6
55 7.2
55 7.7
55 7.3
55 7.1
55 7.2
55 6.5
55 7.2
55 7.2
55 7.1
55 7.1
55 6.9
55 6.5
55 7.1
55 7.3
55 6.5
55 7.2
55 7.2
55 6.6
55 6.6
55 6.7
55 7.0
55 7.0
55 7.4
55 6.8
55 6.5
55 6.9
55 8.0
55 6.7
55 7.2
55 6.2
55 7.1
55 7.0
55 7.2 -45 mean = 7.2235, standard deviation = 0.4236, n=17
-50 mean = 7, standard deviation = 0.4567, n=22
-55 mean = 7.0235, standard deviation = 0.3790, n=34 95% CI for true mean of 205/45 tread width
(7.006, 7.441) 95% CI for true mean of 205/50 tread width
(6.7975, 7.2025) 95% CI for true mean of 205/55 tread width
(6.8913, 7.1557) Notice that all of the confidence intervals for the true mean overlap? That suggests there is no evidence that the tread widths between different aspect ratio tires are different. Here's the printout of the ANOVA. Source DF SS MS F P
aspect ratio 2 0.578 0.289 1.69 0.192
Error 70 11.992 0.171
Total 72 12.570 S = 0.4139 R-Sq = 4.60% R-Sq(adj) = 1.88% 
Once again, confirming that there is insufficient evidence to suggest that aspect ratio impacts tread width. Have a nice day.
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