How to Correct Change of speedometer by tire size changing
 

Hi
I want to have a smoother ride so I have to change tire by a higher aspect ratio
1- Is it remarkable changing from 50 to 55 ?
if I change aspect ratio from 50 to 55 ( 225 50 R 17 to 225 55 R 17) there will be a little change in speedometer .
2-Is there any parameter in ECU to change the tire size and speedometer changing corects?

Year and model of your car?

Under the assumption there is a setting which can be changed for your car, switching from 225/50 R17 to the same model/brand 225/55 R17 tire won't really do much for smoothing your ride as it will only add about 0.45" to an already tall(ish) sidewall height. Your better bet would be to find a softer 225/50 R17 tire and/or changing your shocks to softer aftermarket units.