jadnashuanh
Posts: 4488
Joined: Thu May 22, 2014 2:07 pm
Location: Nashua, NH USA

Re: NON OEM wheels & tires (wider)

Thu Apr 04, 2019 5:12 pm

I wonder how many of those tires available in Germany have the low rolling resistance of the Bridgestone that was purpose built for the i3.

The only way to get a taller sidewall would be to use a smaller diameter wheel if you want to retain the overall diameter that would keep the gearing, speedometer, and odometer accurate. Don't know if there's enough rotor and caliper clearance for that. That would also likely increase the contact patch and therefore rolling resistance.
Jim DeBruycker
2011 535i x-drive GT, 2014 i3 BEV

joeguzman10
Posts: 4
Joined: Tue Nov 06, 2018 6:45 am

Re: NON OEM wheels & tires (wider)

Fri Apr 05, 2019 7:34 am

I wouldn't care about efficiency if the tires have, longer life, less expensive, and possibly safer.
Someone mentioned using size: 215 50r18 which widely available.

My question is will standard rims work?

jadnashuanh
Posts: 4488
Joined: Thu May 22, 2014 2:07 pm
Location: Nashua, NH USA

Re: NON OEM wheels & tires (wider)

Fri Apr 05, 2019 7:11 pm

If I ran the numbers properly, that wheel/tire combination would be about 1.1" smaller in diameter, which is about 4% off of the stock combination in circumference...that would mean your speedometer and odometer would be off by 4% on top of the speedometer's approximately 2mph buffer it builds in. You'd be putting 4% more revs on the motor as well.
Jim DeBruycker
2011 535i x-drive GT, 2014 i3 BEV

benrk
Posts: 9
Joined: Tue Mar 12, 2019 7:17 pm
Location: Winnipeg, MB, CDN

Re: NON OEM wheels & tires (wider)

Fri Apr 05, 2019 8:23 pm

The rims actually are not the problem, 3 piece rims can be configured to diameter, width & offset as desired, it’s just expensive, but not a technical hurdle. The true problem is indeed the tire size. Large diameter tires usually are fairly wide, providing a much larger contact patch than the i3 has from factory, which greatly increases rolling resistance and thus eats into the already rather low range of at least early model i3s. Besides, there simply is no space in the wheel housings for wider tires & you’d have to run pretty wide fender flares or custom build something reminiscent of an ‘80s groub B race car or Rieger wide body kit, I personally don’t consider that very desirable. If you don’t want to run something ridiculously wide, you’ll probably have to shrink overall diameter/circumference to come down to something more reasonable like 195 or 205. You’d probably still be looking at a rare tuner size or steering tire size for RWD sportscars, which will just as much have very limited tire choices & you’ll still need fender flares & lose ground clearance while increasing the arch gap. The best thing we can all do is communicate with big tire dealers like Tirerack or Discount Tire in the US & voice our desire for more tire choices, so maybe they’ll start bringing some of the European options in and talk to the manufacturers to offer more tires.

alohart
Posts: 1676
Joined: Sat Nov 01, 2014 7:36 pm
Location: Honolulu, HI

Re: NON OEM wheels & tires (wider)

Sat Apr 06, 2019 1:02 pm

benrk wrote:Large diameter tires usually are fairly wide, providing a much larger contact patch than the i3 has from factory, which greatly increases rolling resistance and thus eats into the already rather low range of at least early model i3s.
This had been my belief until I was shown the error in my ways. The size of a tire has no bearing on the area of its contact patch, only on the shape of the contact patch. The contact patch area is equal to the weight the tire is supporting divided by the inflation pressure. E.g., in an approximation for an i3 rear tire, area = 750 lb. / 41 lb./sq. in. = 18.3 sq. in.

If a wider tire were installed on an i3 and inflated to the same pressure as the original tire, its contact patch area would be identical but would be wider and shorter (in the rolling direction). The rolling resistance of a wider tire might be less because the sidewall would not deflect as much to form the contact area needed to support the weight. Probably most important, if the wider tire were not be designed as a low rolling resistance tire, the wider tire would have greater rolling resistance than the original low rolling resistance tire. Regardless, the aerodynamic drag of a wider tire would be greater.
Aloha,
Art

2014 BMW i3 Arravani Grey, Giga World, Tech + Driving Assist, Parking Assist, DC Fast Charging, JuiceBox EVSE

benrk
Posts: 9
Joined: Tue Mar 12, 2019 7:17 pm
Location: Winnipeg, MB, CDN

Re: NON OEM wheels & tires (wider)

Sat Apr 06, 2019 1:32 pm

alohart wrote:
benrk wrote:Large diameter tires usually are fairly wide, providing a much larger contact patch than the i3 has from factory, which greatly increases rolling resistance and thus eats into the already rather low range of at least early model i3s.
This had been my belief until I was shown the error in my ways. The size of a tire has no bearing on the area of its contact patch, only on the shape of the contact patch. The contact patch area is equal to the weight the tire is supporting divided by the inflation pressure. E.g., in an approximation for an i3 rear tire, area = 750 lb. / 41 lb./sq. in. = 18.3 sq. in.

If a wider tire were installed on an i3 and inflated to the same pressure as the original tire, its contact patch area would be identical but would be wider and shorter (in the rolling direction). The rolling resistance of a wider tire might be less because the sidewall would not deflect as much to form the contact area needed to support the weight. Probably most important, if the wider tire were not be designed as a low rolling resistance tire, the wider tire would have greater rolling resistance than the original low rolling resistance tire. Regardless, the aerodynamic drag of a wider tire would be greater.
Now that is really interesting, I never thought of it, but it makes perfect sense!

So what does that mean? You’d have a large diameter tire with a wide contact patch & a weight rating that’s likely a fair bit higher than what the i3 needs. So that gives you a very wide and very short contact patch, probably shorter than the tread pattern was designed for. Yes, it will increase wind resistance, which actually is of lesser importance for a city car that’s primarily racing from stop light to stop light. Hydroplaning risk also is greater, but once again not really relevant at city speeds. Anything else?

alohart
Posts: 1676
Joined: Sat Nov 01, 2014 7:36 pm
Location: Honolulu, HI

Re: NON OEM wheels & tires (wider)

Sat Apr 06, 2019 1:57 pm

benrk wrote:Now that is really interesting, I never thought of it, but it makes perfect sense!
That was exactly my initial reaction to this revelation.
benrk wrote:So what does that mean?
We know that drag racers discovered that a wider tire provides better drag racing traction even thought its contact area is no greater. Maybe for drag racing, spreading the acceleration force and resulting heat over more tread works better.

Modern sports cars use wider tires because their cornering traction is superior to that of narrower tires. Not sure why.

Assuming the same rubber compound, a wider tire would probably last longer than a narrower tire because the same tread is in contact with the road for less time as the tire rotates. This could be one reason that i3 tires tend to wear faster than other tires.
Aloha,
Art

2014 BMW i3 Arravani Grey, Giga World, Tech + Driving Assist, Parking Assist, DC Fast Charging, JuiceBox EVSE

Lesterbmwi3
Posts: 24
Joined: Mon Sep 25, 2017 12:32 pm
Location: USA- NewYork

Re: NON OEM wheels & tires (wider)

Sat Apr 06, 2019 7:17 pm

I notice better mileage on ecopia than blizzak my driving in NY is 2000 on ecopia and 1000 miles on blizzak obviously i m driving about 3000 miles a year I’m using this car as an go cart driving around in Staten Island NY and Iove it is 2014 only 14000 miles so far no problems my concern is when my 12V battery going to dye 5years. Old bc you stack without 12Vpower any input about 12Vbattery how you people dealing with ?Thanks if you have any problems to share ?

Lesterbmwi3
Posts: 24
Joined: Mon Sep 25, 2017 12:32 pm
Location: USA- NewYork

Re: NON OEM wheels & tires (wider)

Sat Apr 06, 2019 7:36 pm

Is only car with 5” tires and I pass all BMW 3 series with 7/8 width tires why you need bigger tires I’m playing with guys on o road with Gus guslers bmw’s you faster in 60 miles range than all 90% cars on a road what wider tires help you with? You have to learn how to take advantage of low gravity car and direct torck Ex racer car driver

Lesterbmwi3
Posts: 24
Joined: Mon Sep 25, 2017 12:32 pm
Location: USA- NewYork

Re: NON OEM wheels & tires (wider)

Sat Apr 06, 2019 8:00 pm

Your wider tires don’t make race car spend $ 250000 on electric car and you have a race car be happy you own Bmw I 3 is a faster car on a street in small package/ Race car driver /and know the 2014 BMW I 3 with 60 amp hr battery is the fastest go card on the road!!!!!!! The first production of Bmw

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