Tyre size difference

[LittleZ4]

Afternoon all,
How much difference will z4m tires make on my non m.
I have 8.5j fronts and 9.6j rears, current running 225/40/18 and 255/35/18 tyres respectively.

The car is lowered on coilovers.

Will running 225/45/18 and 255/40/18 make a huge difference?? Eh: rubbing, Speedo ect.....

 

[Conrod]

There you go:

https://www.tyremen.co.uk/tyre-size-calculator

 

[LittleZ4]

Cheers Alan. I suppose the following from that is will this rub?
My fronts have a 5mm spacer, the rears have nothing. I wish I could remember the et on the alloys

 

[Jembo]

will this rub?

Lowered & any participation in a Forum Hoon IMO = yes :rofl:

 

[DaveD]

I run 225/45/18 square on ET34mm offset 405M wheels. It’s on sport springs and B6 dampers with max camber (pins pulled). At full compression in rubs slightly on the liner just behind the headlight. Not a lot but enough to wear a little bit away. With a touch more camber and ideally a bit of extra castor it would be perfect. Camber/castor plates are on the shopping list. If you drive the car hard over rough roads, the extra sidewalk is noticeable.

 

[Stevo1987]

I don't think size makes a difference.

 

[kis]

I ran 224’s in an OEM M fitment. Rears are fine, you’ve got room there for an extra bit of sidewall. The fronts I found to rub slightly, mostly was on full lock, or if during the drive the suspension was changed suddenly, like when you hit a pothole. It could be worse if you’ve got brand new rubber as effectively this will increase the diameter of the wheel further.

For me, optimal would be to run oem at the front and M at the rear. 225/40 and 255/40

Everything is subjective... it depends how lowered you are? And I’m not sure about your offsets for your wheels... and 9.6J rear? Really? .6? As I said rears should be fine, fronts? Well no harm trying it!