Theory question What will be better a 17" rim with 45 profile
Or 19" rim with 30 profile same tyre on both rims and same widness
Im under the asumption that the 17 will be better Due to tyre twist will hug the road under load just my guess

Im just gettin into handaling side of things and want to understand a little more
So if you could ancer in detail please explaning laws etc....

 

Both have a similar sized contact patch.

The 17" will tolerate small bumps during cornering without losing traction, since the sidewall is thicker. I assume that a 30 profile would offer a rewarding level of responsiveness on a glass smooth track.

Wheel and tire mass, or more specifically, moment of inertia determines how easily your horsepower can spin the wheels. Nobody really measures moment of inertia for wheels and tires, but it can be roughly compared by weighing the wheels and tires. Pound for pound, tire mass matters the most because it is at the outer edge of the spinning wheel, and moment of inertia goes up by the square of radius.

So if the 17" wheel is 15 lbs, with a 20 lbs tire...

And the 19" wheel is 18 lbs with a 17 lbs tire...

The 19" combo will have a slightly better moment of inertia, because its mass is more centralized in the wheel.

On the street, the 19" is much more likely to dent and deform from potholes and lips, especially on the inboard side of the rim.

And finally, in general, RX-7 owners like 17" and 18" wheels for performance purposes. 19" is pretty huge. I would choose the 17" wheel for an RX-7.

 

Nice thaks for responce im begining to see a good picture of turing effort on rim sizes
Thanks realy good explanation
So from what you are saying is that the bigger rim is wasting energy and turing force
Ok
So the why not use 16" rims but realy wide turning effort would be reduced

 

That's what Mazda thought, since stock FDs come with 16x8 wheels (pretty wide for a stock car in the 90s).

 

lol tell that to chevy. 17x11's on some vettes