Re part of the safety features...
I keep reading folks making some sort of issue about this when ever we start looking at wheel tire options...
I suppose that nobody wants to think about it for a moment...
Yes the suspension and much of all this car is deliberately designed to absorb crash energy in as few inches or feet of crumple zone as is practically possible...
I fail to see how a Smart 3~4 inch wide steel wheel vs a Smart 5.5~6 inch wide alloy wheel is factored in to the safety concern... How is having a 6.5~7.5 wider alloy any more or less safe?
Or are all the folks fretting about this, unaware that there are already a lot of combinations... including many MB approved aftermarket versions? (Think Brabus and Lornser)
The only issue at all is Clarence and overall tire diameter
There is a max wide tire that will fit under the wheel well...(I don't know how wide max is yet).. 195mm in front and 205mm in back is repored to still be inside the wheel well and not rub on inside under normal suspension compression or tight turning
Stock tire diameter is 22.3" front and 22.6" rear...We have to stay close to these diameters to keep the ESP, traction control, Anti lock, and speedo happy..
You can safely use any Alloy or Steel wheel that fits.....They are all equally safe or dangerous depending on point of view...
There is a legitimate concern using the 3 to 5 lug adapters.... they change the 3 lug 112.5mm to 5x 112.5mm
While they will allow fitment of a broader range of MB wheels they add width dimension. If you do not allow for the wider track with a compensation in the wheel offset you run the risk of added stress on the hub and bearings...
Mechanically, and from a engineering perspective, there is no added or inherent danger with the adapters....