I read about Proton S70 review mentioned that the entry level uses a 205/55R16 tyre.
I had a old camry which I had just changed very recently for 4 * 205/65R15 tyre.
Using this tyre model I had done some checking, Toyo CR1, I found that the
205/55R16 - Price RM272 per pc
205/65R15 - Price 245 per pc.
Both shopee online competitive price from the same shop.
However it seems to me that 205/55R16 is a slightly smaller tyre as per the following :-

The question I had in my mind is 205/55R16 tyre costlier to manufacture than a comparable 205/65R15 tyre ???
Isnt 205/65R15 more costly to manufacture cost wise since it had a slightly bigger lump or rubber & perhaps metal??? Same width, more sidewall and a slightly higher tyre overall than 205/55R16
Or the cost is mostly similar (or very small difference) but the marketing decided that 205/55R16 will price higher than 205/65R15 since as per your statement above, R16 must have better margin than R15 regardless???
This wont be an exact answer, but its more generic. In manufacturing the overall cost of an item depends on the volume of the item being produced. As the volume of a particular item being manufactured increases, the cost of it will reduce. This is call the economics of scale. The same applies for the various tire sizes.
A more common tire size like myvi's 175/65R14 would cost less per tire to produce compared to a more uncommon size. Depending also on the market segment, tire manufacturers can either pass on these savings to the customers by pricing their products competitively or pocket the savings as more profit for the company.