19" or 20" wheels?

And it looks like the 20 inch tyres are actually the same weight (front) or heavier (rear) than the 19's. There goes any weight advantage from the lower profile tyre on the 20's!



http://www.tirerack.com/tires/tires.jsp?tireMake=Bridgestone&tireModel=Ecopia+EP500 (look in the 'Specs' tab).

I33t said:

And it looks like the 20 inch tyres are actually the same weight (front) or heavier (rear) than the 19's.

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Thanks for finding and posting the numbers. Sometimes I wish I weren't so much against betting on anything other than sure bets!

Rubber is heavier than aluminum per volume, and in at least the case of the rear, going from 19" to 20", there is the same or more rubber volume removed in the tire sidewalls than aluminum added in the spokes and rim of the wheel.

I33t said:

And it looks like the 20 inch tyres are actually the same weight (front) or heavier (rear) than the 19's. There goes any weight advantage from the lower profile tyre on the 20's!

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LOL...some of us actually just bought the 20 in wheel style because we think they look better! And I live in Northern California where we don't have to worry about
that silly "winter" tire problem

i3Alan said:

Rubber is heavier than aluminum per volume, and in at least the case of the rear, going from 19" to 20", there is the same or more rubber volume removed in the tire sidewalls than aluminum added in the spokes and rim of the wheel.

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No it isn't

http://www.reade.com/Particle_Briefings/spec_gra2.html


Tyres have steel belts in them, but I doubt that will make up the difference, and the bit you are talking about, (the sidewall) is thinner than the tread and with no steel belts....

kevinb61 said:

I33t said:

And it looks like the 20 inch tyres are actually the same weight (front) or heavier (rear) than the 19's. There goes any weight advantage from the lower profile tyre on the 20's!

Click to expand...

LOL...some of us actually just bought the 20 in wheel style because we think they look better! And I live in Northern California where we don't have to worry about
that silly "winter" tire problem

Click to expand...

I think you have found the only good reason to buy them!

Summer tires do not work anywhere near as well when the temperature gets below 40-degrees F. Much less grip, so therefore, lower g-force, and longer stopping distances. Above 40 or so, a summer tire is generally engineered to provide better performance. This is regardless of any precipitation. Now, depending on where in NCal you are, it may not snow much, if at all where you'd be taking your i3, it might get colder than 40. They stopped calling them snow tires ages ago for a reason...they're a cold weather/crappy weather tire.

jadnashuanh said:

Summer tires do not work anywhere near as well when the temperature gets below 40-degrees F. Much less grip, so therefore, lower g-force, and longer stopping distances. Above 40 or so, a summer tire is generally engineered to provide better performance. This is regardless of any precipitation. Now, depending on where in NCal you are, it may not snow much, if at all where you'd be taking your i3, it might get colder than 40. They stopped calling them snow tires ages ago for a reason...they're a cold weather/crappy weather tire.

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OMG...you guys are something.... I have driven on nothing (OK...except my pickup) but NON "cold weather/crappy weather tires" for years, and years, with no problems, on many cars (corvette, z4, sl55 amg, clk500, etc., etc.). If you feel the need to swap tires, good for you. For some of us...it's no problem.

And picking a tire/wheel combo that you think looks the best is a problem....sigh...yea....cause my i3 is such a performance car. If I want to drive that way, that is
what my '11 Z4 3.5is is for.

Interesting points.

Winter wtyre contain much more real rubber than normal road tyres. In terms of composition (from www.wrap.org.uk):

"A common-sized all season passenger tyre made by
Goodyear, weighing about 10 kG (22 lbs) new, contains:-

• 30 kinds of synthetic rubber
• 8 kinds of natural rubber
• 8 kinds of carbon black
• steel cord for belts
• polyester and nylon fibre
• steel bead wire
• 40 different chemicals, waxes, oils, pigments, silicas & clays."

Overall rubber/elastomers make up 47% of the weight of a standard tyre. Carbon black 21.5% and metal 16.5%.

A third of the rubber used is in the outer tread and a fifth is in the sidewall by %weight rubber."

and from http://www.tuneruniversity.com/blog/2011/04/wheel-tech-part-iii-wheel-diameters-effect-on-performance/

"Small sidewalls are very stiff, great for cornering “feel” but terrible for ride quality and straight line stopping and acceleration (more on that later). Stiffer sidewalls do not give any additional grip.

As the sidewall size goes down, the weight of the tire stays the same or gets bigger.

However, as a result of an increase in wheel diameter, this makes the weight distribution of the wheel+tire combo worse – the heaviest part (the tire) is now further away from the center of the wheel – refer to Part I for why that’s bad. In short, it robs precious power from getting to the road. Many guys spend so much time focusing on the wheel weight but never even think about the tire weight and its effect on the weight distribution of the wheel.

Warning: Never make the mistake of choosing a TIRE by its weight. Usually a tire’s weight is directly proportional to how much reinforcement is inside the tire. Cheap tires are often lightweight, but only because they cheeped out on the sidewall reinforcement. I actually had a popular cheap tire go out of round because it was so cheaply made inside. Choose tires based on tread and compound – never by weight. DO consider the weight of the tire when picking the size of your wheel, however.

Larger sidewalls allow better ride quality, better straight line launch, braking and do not necessarily decrease grip but may make the car handle less precisely. In other words, the sidewall flexes so the steering response will be slower and you get a lot more “roll” in the bends. Too big of a sidewall can cause excessive tire temperatures due to a lot of flexing about and possible failure in race conditions so it still is ideal to keep relatively low profile sidewalls on performance applications as we mentioned earlier.

You’ll notice that drag racing slicks always have very tall sidewalls. You never see low profile drag slicks. This is because when a drag car launches, the tire actually deforms and ripples up to create an even fatter patch of rubber on the ground and to generate ‘bite’ into the ground. The smaller the sidewall you use, the more likely you will spin your tires off the line. Taller sidewall tires can generally bite harder both under braking and acceleration.

If you’re looking to fit wheels that weigh less than stock, the larger you go in diameter, the more difficult and expensive it will be to find a lighter than stock wheel."

kevinb61 said:

OMG...you guys are something.... I have driven on nothing (OK...except my pickup) but NON "cold weather/crappy weather tires" for years, and years, with no problems, on many cars (corvette, z4, sl55 amg, clk500, etc., etc.). If you feel the need to swap tires, good for you. For some of us...it's no problem.

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Cold for many parts in CA is 50-degrees, and yes, a summer performance tire will operate fine. Take a true summer performance tire up into the mountains in the winter and see how well they get you through, even if the roads a clear, at down below freezing, you will not stop or corner as well. TireRack (and others) regularly do testing, and the differences in safety margins are more than trivial.

this is a great thread. but which one performs better in handling?

I drove the stock Mega and couldn't belive the roll and felt unsafe. I the Giga 19 and 20's I felt the both performed better.

But, I didn't drive enough 19 vs 20s to compare.


Weather conditions, not being part of the equation.

thanks!

The 20" wheels/tires have a shorter, stiffer sidewall, and since the tread is quite similar, should handle slightly better at the expense of ride comfort. Others have also reported that in a turn, the 20" tires make some noises that the 19" ones don't. The 20" being a summer performance tire has different rubber, but the advantage goes away entirely when the temperature drops to below 40-degrees F. Being slightly wider, they also create more drag, and thus will affect the overall range slightly.

Ultraturtle your wife and my wife must be related. Normally sensible, when it comes to her car it's the sky is the limit, and must be replaced every 3 years when the nail polish wears out and it must cost 5 grand more than the last one... . And don't even think about NOT putting the best stereo available in it. And ANY noise that comes up from anywhere on the car makes her want a new one. Why me? :twisted:

I got to test drive the i3 at the dealer in a nice spirited jaunt on the 19" wheels. Of course I was hooked. But I could never buy this car without the 20" wheels because I hate the look of all the other ones available for it. I expected the 20" wheels to handle different, but it's not nearly the difference and sound increase I thought it would be. I would expect that if BMW offers it, then it must be okay. The 20"wheels do have a bit more road noise at lower frequencies but worth it for the look for me.

I did alot of wheel size/tire swaps on my Jag Vanden plas and I could not believe the difference in ride quality on those cars and going tire to tire. Some were absolutely horrible but as one poster remarked, it's absolutely true that the sidewall of the tire makes all the difference in the world in ride quality. FOund that out the hard and expensive way. Personally I am very impressed by the ride quality versus the tiny rubber height of the 20" wheel on my i3.

DeafSoundGuy said:

Ultraturtle your wife and my wife must be related. Normally sensible, when it comes to her car it's the sky is the limit, and must be replaced every 3 years ...

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Actually she drives her cars for 10 years or more, but keeps them in pristine condition. This one is so sweet, I think we may keep it for 20!

Personally I do not like the look of the 20” wheels. Happy that my Giga came with the turbine style I prefer. Though I wish BMW offered the 19” summer performance tire option. Bridgestone makes them because the Tire Rack has them in stock. I’ve already decided I’ll switch to them when it’s time to replace the original rubber. I see no reason to continue with the performance compromises of all seasons in San Francisco where temperatures have dipped below 40º F overnight maybe four times in the 19 years I’ve lived here. Also, I’ve had no issues with the summer tires on my ’09 E90.

Hi guys,

my first post! Regarding the 19 inch vs 20 inch I have driven both multiple times, and there is no question in my mind that the 19 inch provides a smoother ride and is overall best. The 20 inch are harder and I imagine much easier to flat if you are unlucky with a pothole in addition to damaging the wheel. I would recommend the 19.

David

Welcome!

I have the 20's and after doing a couple of 500 mile days, I have to say that the tires are very noisy: on any sort of rough or even worn pavement they make a terrible roaring noise that is very tiring.. No problem on smooth new asphalt, but on anything else they are not acceptable from a noise and vibration standpoint.

I have the 20s and have also driven 2000+ miles on 19s - I wouldn't even consider going with the 19s, since I prefer the additional grip and don't mind sacrificing some ride quality.

I know others who prefer the 19s since ride quality (or the look of one of the 19" options) is the highest priority for them. I would suggest doing a few test drives of each if you're on the fence, then go with the ones you like.

I agree with one of the above posts about BMW offering the summer compound in the 19" size - that might provide the best of both worlds - improved grip and better ride quality.

It's probably best to ignore any posts that say one option is the best for everyone

You won't notice the difference.

Yes, do you really notice the difference or is this a mental thing? I'm looking at one with the 20" not because I want them but because the car has everything else I want. I'm nervous because the 19" already felt stiff to me. (Don't care about winter issue...in CA.)