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View Full Version : Tire sizes & rotation...is the manual wrong?



rnddude
10-07-2013, 04:44 PM
OK, the 500e manual claims different size tires and/or wheels on the front versus the back, and as such can only be cross-rotated. However, on every 500e I have seen the tire sizes are identical...185-55-15, and the wheels appear to be identical also, so why the discrepancy? :confused:

webwevers
10-08-2013, 04:16 PM
From my understanding the rear wheels are wider then the front wheels. This is what I found out when I looked into it.

The wheels can only be rotated side to side. Just like the Crossfire and Viper.
The Wheel width's are different front to back. The 500e needed the wider wheels in back to help manage the battery weight distribution.
Wider wheels increase lateral stiffness in cornering.

rnddude
10-08-2013, 05:02 PM
webweavers, you are correct. Same size tires, but 1/2" wider wheel in the rear. After thinking about it, I suppose the rational to having the same size tires on different width wheels is this: stretching a smaller tire onto a wider rim effectively stiffens the lateral deflection (although at the expense of vertical compliance and harshness over rough roads) which would be good on the relatively tail heavy (batteries) 500e during aggressive cornering. The same tire on narrower rims on the front would yield better ride quality than the rear setup.

However, the width difference is so small, I really wonder if the improvement is really very profound.

Fiat500USA
10-09-2013, 12:29 AM
They spent a lot of time developing the character of the 500e and wouldn't go to the expense of the wider wheel if it weren't that important to the feel and stability. Maybe you could borrow a set of wheels from a friend and see how it feels. I'd say there would be an increased propensity for oversteer especially in transitions. That may or may not be a problem for you, but that can catch you if you aren't 100% on your game at the time.