does anyone know, how much does rim size affect on acceleration and speed?

 

Not so much the speed, the worse part is distance traveled.

 

What do you mean, the gas consumption goes higher?

 

No, difference tire sizes will cover diferent distances in one revolution.

 

typically bigger rims can also be heavier = slightly worse gas consumption, shorter break life, and can effect acceleration.... that being said, rapidly increase cool factor. As Afretes mentioned - tire diameter doesn't change so speedometer/odometer etc not effected.