What about the aerodynamic effect. Shouldnt you also try to get same 10 degree "kammback" shape on to the tire to lower their aerodynamic resistance?
That I will try to test this summer also on my Lupo. Try to stretch the rubebr to 10 degree angle.
I agree that effect to diameter does not have measurable effect, but what about the aero?.
I have my own eco tire designed for less aerodynamic drag wise plus some other tricks, but Nokian Tyres did not see that that kind of tire would fill their requirements for tires they have.
I can send the file to any tire maker who is willing to make the first tire to my lupo size spec
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