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[Si-M240i]

Is there any reason that I couldn't fit 255 35 18 to replace the 245 35 18 on the rear and fit 225 40 18 to replace the 215 40 18 on the front ?

it is only a 1% difference for the speedo but I get so much wheel spin I wanted a bit more rubber on the road to reduce it. I do not want to go to NON RFT's.

[BMW86]

Yes that is what most people replace their runflats with. I am running it as well, it's an improvement.

[Si-M240i]

Originally Posted by BMW86

Yes that is what most people replace their runflats with. I am running it as well, it's an improvement.

Thanks. Did you notice any difference in accelleration due to ratio change, or is it just as quick......if not quicker as less wheel spin in 1st ?

[Red Bread]

Originally Posted by Si-135i

Thanks. Did you notice any difference in accelleration due to ratio change, or is it just as quick......if not quicker as less wheel spin in 1st ?

You're unlikely to notice any acceleration differences from a 1 cm change in tire width, and if you're changing from the OE runflats to non-runflats, you'll be taking weight off, which should very slightly help acceleration and will very slightly improve mileage.