Wheel sizes

[Spurdog79]

Hi guys,
I have a BMW 435D XDRIVE GRAN COUPE. I was worried about changing my wheel size.
I currently have 20inch wheels and I can feel every bump and pothole. I'm thinking of going down to 18inch but worried about effecting the ECU has anyone done this and how did it go for you please

 

[Eddie208]

I've not done this, but changing the suspension, the springs, would create a bigger change to feeling the bumps no?
Instead of lowering springs, higher ones and with more stability, over the usual lowering performance ones.

 

[Spurdog79]

I've not done this, but changing the suspension, the springs, would create a bigger change to feeling the bumps no?
Instead of lowering springs, higher ones and with more stability, over the usual lowering performance ones.

It would soften the feeling but still smash the tyre flat to the alloy and cut the tyre. There will still be no protection from concrete to metal

 

[TCJBOLDIE]

Don't know if changing wheel diameter and fitting higher aspect tyres to help soften the ride to keep the rolling diameter the same will cause any lights to show on the dash but I would enquire at a dealership OR do a basic google search before making any change from stock.
PS don't forget to advise your insurer of any change from stock.

 

[karenbatten]

Downsizing from 20-inch to 18-inch wheels on your BMW 435D XDRIVE GRAN COUPE is generally possible and won't directly affect the Engine Control Unit (ECU). However, it's crucial to maintain the overall diameter of the wheel and tire combination to avoid triggering potential issues with the vehicle's electronic systems. Consult with a professional mechanic or the car manufacturer to ensure that the new wheel and tire setup maintains the proper diameter and meets the specifications for your specific BMW model, preventing any adverse effects on the ECU or other vehicle functions.