foggy69 wrote: ↑
Wed Sep 13, 2017 1:05 pm
I have not been that impressed by the brakes on my i3.
In an emergency, they seemed to lack the bite I expected. I assumed that the weight of the car and the narrow tyres are contributing factors.
Braking is a function of the tire footprint and the reason BMW went with the larger, narrow tire for the i3 is that it has less drag while moving, but can retain the same footprint as a smaller diameter, wider tire. Total footprint is a function of the vehicle weight and tire pressure. The wheel size will play a part in the shape of the footprint, but not the total size. On the wheel/tire combo in the i3, it is a longer one than wide, versus maybe a square or oriented width-wise you'd get with a smaller wheel. In reality, that might help in traction going straight for either starting or stopping, depending on the tread, and less for cornering.
Because we rely more on regen to slow us down, the brakes don't get used that often. They can develop a coating of rust, but also, if there's much of any gunk that got onto them, it doesn't get worn/scraped away like on a vehicle where the brakes are used constantly. That could affect the end result of your braking force.
The i3 still has a conventional hydraulic master cylinder, so the brakes should work even without power. The ABS unit can play into that if traction is reduced and it detects a wheel slipping, though.