I have been wondering about this!
Can I fit 16” wheels on my 416 Mercedes? It has twin wheels to the rear and is on 15” at the present. I have the clearance within the wheel arches and nothing to rub or catch when I turn the steering.
Why? Well at 60 mph my van is running at 2900 RPM and by increasing the wheel size I would cover more distance with one revolution on 16” wheels. Hence lowering the RPM for the same speed.
I know about the speedo…this can be re calibrated through the ECU.