Square tire setup/Alternate tire size

[N52E89Fan]

Hi,
I'm new to the E89 platform (2011 sDrive 30i), and I'm in the market for new tires. I'm currently running 225/40/18 up front and 255/35/18 out back. i'm thinking about going with a square setup, or potentially wider tires up front (and maybe out back.

Does anyone have any experience with running a square setup on this car (if so what size), or any alternative sizes front/rear? Just seeing what my options are, and trying to reduce some of the understeer as well. Suspension will be coming next, which I know will help more, but I need tires sooner than dampers. For reference, my car is fitted with Style 276 wheels.

Thanks!

 

[Reamesy]

I’m sure the wheels are 8J front and 8.5J rear. So you would need to go with four x 8.5J if you want to go bigger and be true square set up.

I can’t comment on if this will improve anything. Hopefully someone can assist you there.

 

[B21]

On a 30i changing to a square set up isn’t going to reduce understeer in any street based driving..

The E89 is set up with strong understeer to save people from killing themselves…

Changing geometry would have a much greater effect on steering behaviour.

With decent tyres at those sizes there’s adequate grip in all conditions…

For fun / track use wider tyres could be used with suitable wheels..