colinfwi
Posts: 6
Joined: Sun Nov 16, 2014 1:44 pm

Changing the wheels on my i3

Sat May 09, 2015 1:59 pm

It is overdue that I switch from winter tires to summer tires on my i3. I have the summer tires mounted on 20 inch wheels and I have an air wrench but one of the five bolts on each wheel looks strange. What socket do I need to remove and replace the i3 wheels and does anyone know what the torque should be when I tighten the bolts? Any pitfalls I should know about if I change the wheel's myself? The owner's manual says not to do it but the dealer is two hours away from my home and it seems crazy to have to take a day to get the wheels switched over each season! Thanks for your help.

websterize
Posts: 531
Joined: Sun Sep 07, 2014 3:39 pm
Location: Maryland, USA

Re: Changing the wheels on my i3

Sat May 09, 2015 2:26 pm

Are the "strange" ones wheel locks? There might be an adapter in the frunk.

17mm socket on lugs, torqued to 140 nm.
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WoodlandHills
Posts: 751
Joined: Mon Sep 15, 2014 4:50 pm
Location: SoCal

Re: Changing the wheels on my i3

Sat May 09, 2015 2:53 pm

websterize wrote:Are the "strange" ones wheel locks? There might be an adapter in the frunk.

17mm socket on lugs, torqued to 140 nm.
Also step-torque in a star fashion, I would click them at 50, 100 and then 140....
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jadnashuanh
Posts: 5196
Joined: Thu May 22, 2014 2:07 pm
Location: Nashua, NH USA

Re: Changing the wheels on my i3

Sat May 09, 2015 6:17 pm

You need to be careful lifting car. If you don't have a BMW jack, you may want to buy a lifting adapter to fit into the lifting socket otherwise, you may end up cracking it. Other than that, and other BMWs are the same. Depending on the tires/wheels you have, be careful about where you put the new ones! Many of them are directional, both the wheel and the tire. Other than that, it's no different replacing a wheel on the i3 as most any other car.
Jim DeBruycker
2014 i3 BEV, 2021 X5 45e
(The i3 will be sold soon, <17K-miles, interested?)

busaman
Posts: 143
Joined: Wed Dec 31, 2014 11:00 am

Re: Changing the wheels on my i3

Sun May 10, 2015 7:06 am

has anybody thought of trying 18" rims with a higher profile tyre in theory would take some of the harshness out of the ride.
7.31s@203.3mph on one wheel

jadnashuanh
Posts: 5196
Joined: Thu May 22, 2014 2:07 pm
Location: Nashua, NH USA

Re: Changing the wheels on my i3

Sun May 10, 2015 1:17 pm

Unless you went wider, you'd have a smaller tire contact area. I've not been underneath the car to see if a smaller wheel would fit, assuming you could find one. It may also be a challenge finding a low rolling resistance tire in the required size, too. The people that bought the 20" wheels because of the 'look' would laugh! Personally, the 19" ones are decent for my driving, but a lot depends on your local roads and how far you drive it at any one time. My trips are generally short, and the roads aren't too bad.
Jim DeBruycker
2014 i3 BEV, 2021 X5 45e
(The i3 will be sold soon, <17K-miles, interested?)

busaman
Posts: 143
Joined: Wed Dec 31, 2014 11:00 am

Re: Changing the wheels on my i3

Sun May 10, 2015 10:43 pm

jadnashuanh wrote:Unless you went wider, you'd have a smaller tire contact area. I've not been underneath the car to see if a smaller wheel would fit, assuming you could find one. It may also be a challenge finding a low rolling resistance tire in the required size, too. The people that bought the 20" wheels because of the 'look' would laugh! Personally, the 19" ones are decent for my driving, but a lot depends on your local roads and how far you drive it at any one time. My trips are generally short, and the roads aren't too bad.
not true if you had a matched sidewall height the circumference would be the same therefore so would the contact patch (people here in the UK dump the run-flats on the 3 series fit a smaller rim with a taller tyre because the ride is too harsh) for the same rolling diameter.
7.31s@203.3mph on one wheel

i3Alan
Posts: 305
Joined: Wed Jul 09, 2014 4:08 pm

Re: Changing the wheels on my i3

Mon May 11, 2015 2:10 pm

jadnashuanh wrote:Unless you went wider, you'd have a smaller tire contact area. ...
First, smaller/larger wheels are paired with larger/smaller sidewall tires resulting in the exact same diameter treads.

Second, tire contact/patch area is entirely a function of the tire pressure and the weight on the tire.

For example, 500 pounds of weight on a tire filled to 25 pounds per square inch results in 500 lbs / 25 lbs/sq.in. = 20 square inches of patch area.

Wider/narrower tires result in shorter/longer contact patches, assuming the tire pressure is the same.

If the sidewalls are not tall enough to provide the required flex to fit the needed patch area, then you will be riding on the rims instead of the air inside the tire.

engineeringDynamo
Posts: 8
Joined: Mon Aug 07, 2017 8:36 am

Re: Changing the wheels on my i3

Mon Aug 07, 2017 8:56 am

busaman wrote:has anybody thought of trying 18" rims with a higher profile tyre in theory would take some of the harshness out of the ride.
I can't find 16, 17, or 18in rims for the i3.
IMO large rims with low profile tires are a sign that marketing has won an argument with engineering.

jadnashuanh
Posts: 5196
Joined: Thu May 22, 2014 2:07 pm
Location: Nashua, NH USA

Re: Changing the wheels on my i3

Mon Aug 07, 2017 4:54 pm

engineeringDynamo wrote:I can't find 16, 17, or 18in rims for the i3.
IMO large rims with low profile tires are a sign that marketing has won an argument with engineering.
I doubt you will find much smaller wheels that will actually fit on the car. The profile of the stock tires is not particularly low. BMW chose tall, narrow tires/wheels for a specific reason...being narrower, they have less drag. Being taller, they can have the same surface contact area as a smaller/wider tire (although the orientation is different). The i3 is an EV, where drag results in less range. They spent lots of time working out the details.
Jim DeBruycker
2014 i3 BEV, 2021 X5 45e
(The i3 will be sold soon, <17K-miles, interested?)

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