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[jancsi]

Hey guys!

I have had my 320D on the OEM tires and rims since production. Both my summer and winter tires are 205/55 R 16. Since I am going to change my summer tires this April, I was wondering about getting a new set of aftermarket 17" rims, so it looks better.

I have the EfficientDynamics Edition, which has great fuel economy. This is important to me, since fuel prices in Europe are quite high. As I was checking the OEM recommended rim and tire sizes, I found out that BMW fitted 17" rims with at least 225 width tires. However, considering fuel economy I would like my tire's width to remain 205mm. Not sure how much of a long-term impact would this have on fuel economy.

I was checking what the difference in diameter is for several tire/rim combinations and I found out that the 205/50 R 17 tire has a 0.8% difference in diameter, whilst the 225/45 R 17 has 0.3% compared to the current 205/55 R 16.

Is it safe to get the 205/50 R 17 or should I go with the OEM recommended 225/45 R 17? I don't want the hassle of recalibrating the software each summer/winter season, so I want to stick as close to the original wheel diameter as possible.

I also like the skinnier tires, because they allow for a bit of sliding, which I enjoy. I am worried that with fitting 225mm tires the power won't be enough to allow for sliding, since the engine in the ED Edition was downrated to 163hp instead of the 187hp in the normal 320D. Or perhaps I should remap my ECU for 187hp, but then again it will increase fuel consumption. This car is built for economy and I am not sure what increasing engine power would do to the driving feel with its special clutch mass damper and slightly different gearing.

I would be glad to hear your opinions/experiences on this 🙂

[Ruster82]

You say fuel economy is very important to you then say you enjoy sliding which requires using more power this in turn reduces your fuel economy.

Not sure if you know this but the original efficient dynamics wheels are designed to increase fuel economy by reducing drag so swapping to a different set will in turn reduce your economy.

Unfortunatly there is no way to increase power while keeping the same economy, one is always affected by the other.

The differences are so minimal the chance of you noticing a difference in economy from a wheel swap is highly unlikely so i say go with wat you like the look of.

[jancsi]

Originally Posted by Ruster82

You say fuel economy is very important to you then say you enjoy sliding which requires using more power this in turn reduces your fuel economy.

Not sure if you know this but the original efficient dynamics wheels are designed to increase fuel economy by reducing drag so swapping to a different set will in turn reduce your economy.

Unfortunatly there is no way to increase power while keeping the same economy, one is always affected by the other.

The differences are so minimal the chance of you noticing a difference in economy from a wheel swap is highly unlikely so i say go with wat you like the look of.

I meant mostly highway fuel economy, since I'm traveling around 1000km each month. That doesn't mean I don't appreciate the occasional mountain pass drive, where I can play around a little bit. I very much enjoy sporty driving, that's why I love this car. Economical when you need it, but also great when you just want to have some fun.

I know about those special rims they made. However, I got 2 sets of rims for summer/winter season. I am getting rid of the winter set, so I swapped those special aerodynamic BMW rims for the winter. I had them on for summer so far. I want to upgrade the summer look purely for better aesthetics.

Like you said, probably the fuel consumption change will be unnoticeable so I may as well go for the bigger rims and wider tires. Thanks