Our 6i has the 16" alloys. I'd prefer to stick with the stock 205/60 size to keep the speedo and odo accurate. Well, I wouldn't be opposed to going with 215/60 but I don't feel comfortable changing sidewall size.
Also, I have Dunlop SP Sport 9000s on my mustang, and they seem to wear prematurely... other than that I was happy with their performance.
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1. The second number in the tire size designation is a
ratio, not a
size. The nominal sidewall height is that ratio applied to the section width: that is, 60 percent of 205 (equals 123 mm) or 55 percent of 215 (equals 118 mm). Five mm is about 0.2"; the overall tire diameter is about 25.6".
2. It is a rare tire that has a section width of
exactly 205.00 mm, or that has an aspect ration of
exactly 60.00 (percent). All you know from the 205/60 specification is that -- when mounted on the specified mounting rim -- the section width is more than 200 mm and less than 210 mm, and that the sidewall is more than 57.5 percent and less than 62.5 percent of the section width. (In fact, in the OEM tire for the Mazda6 with 17" wheels, Michelin's own data sheets for the MXM4 in the 215/50-17 size show a different actual size -- illustrated by a different number of revolutions per mile -- for the H-rated version than for the V-rated version in the same specification size.) A given 215/55 tire could actually have a taller sidewall than a given 205/60 tire.
3. Your experience with the Dunlop SP Sport 9000 probably does not apply to the SP Sport 01. When the 9000 came out, Dunlop was owned by Sumitomo, the 9000 was designed by Sumitomo, and IIRC the 9000 was made in Japan. Later, Goodyear acquired both the tire operations of Sumitomo (and the Dunlop brand) and the German tire company Fulda. The SP Sport is a German-designed tire manufactured in Germany, though it bears the Dunlop brand. The name on the sidewall is the only similarity between the SP Sport 9000 and the SP Sport 01.
