Tires question I can't find the answer to (I'm slow)

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ddwornik

New member
Joined
Feb 5, 2020
Messages
4
So, I have a 2015 i3 with the 20 inch rims which are both a little uncomfortable and summer only tires.

Short of spending $450/wheel for the OEM 19 inch wheels, it looks like all of my options are to get 4 19x5 rims and just mount the wider tires in the back. Will this lead to notable casual performance issues?

The options I see are the aftermarket wheel and tire package from tire rack (pre mounts the wider on the 5 inch rims in the back) or buying a winter tire package from BMW and using the base rims and putting summer all seasons on them (either 4 the same or wider backs as tire rack suggests).

it looks like spacers and i3s wheels are an option too (maybe?), but not one I'm so interested in.

My real questions are:

1) What is a better option, all the narrow tires on the 5 inch rim, or the wider back tires?

2) what will the difference be between using a wider tire on the 5 inch rim (in the back) vs using stock rims (I assume it will be very slightly similar to using the narrower tires all around, but much more mild since rim width doesn't impact tire width so much).

I'll note, in the last 3 weeks we had 70 degree days and single digit nights, and we don't really get much snow, so I'd much rather have a more comfortable (18 inch) all season tire than swap tires every year, we get very little snow too, it's mostly about temperature and tire wear.

One obvious perk I see to the narrow tires all around is ability to rotate front to back.

Sorry if this is a repost, but all I saw in my searching was information about winter tires or non standard ones.

Is it likely the 4 narrow tires are the best option for me since I won't be pushing the car close to its limits and I may even eek out a mile or 2 of range, and significant tire life with rotations?
 
Hello
The stock 19" rims are 1/2" wider at the rear. All season tires are available with 155mm wide fronts, and 175 wide rears. I have been mounting winter tires on mine, 155 wide for both front and rear. I don't think you can get 175 wide winters.
I hope this answers some of your questions.
 
The stock 19" rims are 1/2" wider at the rear. All season tires are available with 155mm wide fronts, and 175 wide rears. I have been mounting winter tires on mine, 155 wide for both front and rear. I don't think you can get 175 wide winters.
I hope this answers some of your questions.

Not exactly, my question is are there any issues mounting the wider rears on 5 inch rims (such as tire rack recommends), and are their any real benifits to the wider rear tires, is is going with the 155s on all 4 with aftermarket rims essentially good enough.
 
Probably not any problem there.

There are industry standardized matchups of wheel to tire width. My only hesitation is BMW broke the mold with the i3 tires.

But generally speaking, 5" wheels have an industry recognized range of 155 to 185 mm tread. 5.5" wheels bump that range to 165 thru 195 mm tread.

Car owners violate these norms all the time, either to get a stretched fit, or to cram as much rubber on an existing rim as possible. So I don't expect you'd run into any trouble.

So why did BMW go through the trouble of specing a 5.5" wheel when the 5.0 would have been fine with a 175 tire? I'm not sure. Flatter sidewall profile for improved aerodynamics or aesthetics? Different offset wheel to provide additional clearance? That, I'm not sure.
 
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