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      12-24-2018, 10:45 PM   #11
bmwmike01
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Drives: 19 M550 (on order
Join Date: Sep 2018
Location: East Coast US

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Quote:
Originally Posted by .BMW. View Post
Quote:
Originally Posted by SteveMondragon View Post
They're 20" tires that fit both the 5-series and 7-series wheels.... 245/40-20 and 275/35-20. Same size as what you find on the 20" 759i and 669M wheels, which are an available option on the G30 5-series. Difference is the offset of the wheels.
Thanks!

Those are the OEM tire sizes for 7 Series G11/G12. The 5 Series G30/G31 use tires with 1" shorter overall diameter, ie 245/35-20 front and 275/30-20 rear.

G30/G31: 245/35-20, 680 mm
G11/G12: 245/40-20, 704 mm (3.5% taller)

G30/G31: 275/30-20, 674 mm
G11/G12: 275/30-20, 700 mm (3.9% taller)

The result when using 7 Series tires on 5 Series is that the car sits 1/2" higher from the ground, the wheel gap is reduced by 1/2", the speedo reads about 4% lower than with OEM tires and the odometer accumulates 4% less miles than you actually driven.

Taller tires will also increase comfort, and affect both acceleration and fuel consumption.

I am sure you are aware of all this, but it could be good info for other people reading this thread.
Hey, I listened to your advice and got the +5 on the side wall for my 668m rims. It's been good so far thanks! What do you mean affect acceleration and fuel economy, would this be in a positive way or negative way?
Appreciate 0