Test: comparing Blackfly vs. ForkenSwift rolling resistance (Goodyear Invicta GL)

[MetroMPG]

Another drive/charge cycle on the ForkenSwift with the Invictas: 227 Wh/mile = 3rd best efficiency of 2009.

The tires are now back on their rightful vehicles. But before I swapped them back, I did some more comparisons this evening: coastdown testing to compare the two different sets of tires on the ForkenSwift.

This time it was on as level a road as I could reasonably find within range of the car, 30 down to 10 km/h, multiple bi-directional runs. I'll post the results later or tomorrow.

(Might be useful to start a wiki page listing coastdown values of various cars, showing tire brand, pressure, vehicle weight, ambient conditions. Might be useful as a tool to gauge how good or bad your rolling resistance is, relative to other cars.)

Also weighed them: Invicta + steel rim = 27 lbs; snow tire + steel rim = 29 lbs.

[MetroMPG]

Another drive/charge cycle with the Invictas on the ForkenSwift: 2nd best ever efficiency @ 212 Wh/mile / 159 mpge (US) over 36 km / 22 mi. (Of course not representing "normal" driving - about 1/3 of the total distance was coastdown testing!)

Coastdown times quantified: the Invictas KILL the snow tires. I was surprised by the measured difference:

[MetroMPG]

Another update - the first drive/charge cycle with the snow tires back on and power consumption has returned to mediocrity: 280 Wh/mile vs. 212 last time (with the Goodyears).

I'm planning to fix this problem. That's just too massive a difference to ignore.

[hobbes]

Hi MetroMPG
Wow! Just found this thread... Must be because I spend most of the time lurking in the Fossil Fuel Free threads.
Now thats extreme dedication! Swapping all four tyres on the street! Great stuff!

[MetroMPG]

Thanks, hobbes.

Now I just need to get four non-snow 155/80/13 tires onto the ForkenSwift! The difference is too much to ignore.