Visualize whirled rubber:
205/55R16: sidewall height 112.75 mm, circumference 1985.17 mm, ride height radius 315.95 mm.
215/55R16: sidewall height 118.25 mm, circumference 2019.73 mm, ride height radius 321.45 mm.
(Dimensions courtesy of McGrefer UK.)
If you can distinguish the two at a glance, you have better sight than I do, Gunga Din.
Yesterday I was making the Long Trip (a bit over 10 miles) home, and noticed that Gwendolyn was favoring her right side just a little: nothing heinous, but nothing to be encouraged either. First stop was the Oklahoma Gazette office, to snag a copy of the alt-ish weekly, and as I returned to the car, I saw: whatever the heck that was, it was a long way from 33 psi.
Okay, fine. I’ve got just enough time, and probably just enough inflation, to make it to the tire shop. Let them worry about it. (Probably just random storm debris, of which we have an abundance of late.) The shop duly looked over the offending tire, and pronounced it fixable, maybe — but these things are five years old, and they won’t last much longer.
Still in “okay, fine” mode, I bade them replace the lot. Which they did, although they ran a bit past closing time. Handling seemed a little squirrely, but I attributed that to unfamiliarity with the new rubber.
But then I got home, and the shadow on the garage wall looked, well, wrong. Just a little too short. I fetched a light and inspected the sidewall. Yep: they’d put on 205s instead of 215s.
So the tail end of this afternoon was devoted to swapping them out yet again. (I’d run up just under 30 miles on the 205s.) No harm, no foul, but still plenty weird.
As for the tires themselves, they’re Cooper CS4s, which have the dual distinction of (1) being made in the States and (2) being offered by no automaker anywhere as OEMs. Compared to the old Dunlops, they’re one speed rating lower — H instead of V, though since the actual OEM specification is for H, this presented no issue — and a bit more relaxed on crummy pavement, of which we also have an abundance of late. I didn’t need a $700 hole in the pocketbook just now, but there’s no point in prolonging the inevitable.
Sort of aside: We are told that the treadwear ratings don’t necessarily imply anything, other than that a 200-rated tire will last twice as long as a 100. The OEM Bridgestones on my old Mazda, which bore a 500 rating, crapped out at 50,600 miles. The Dunlops being replaced were rated at 460; they made it to just over 43,000. I reserve the right to draw whatever conclusions I want from this. (CS4: 560.)