How do you justify 19inch Rims over 18s on your 1M?

[niuniu]

Say it comes as standard with 18s (some alloy we haven't seen yet I'm guessing), but the upgrade options are 18 or 19 inch M3 Competition alloys (the ones we see on the Valencia teaser car)..

How do you justify the 19s? I'm guessing the car would be slower with them on - what's the trade-off in benefit, more grip?

[Dackelone]

The prototype 1M in Valencia, Spain had 19's on it. Same sizes as the orange car at OctoberFest in Ga.

[fly135]

Originally Posted by niuniu

Say it comes as standard with 18s (some alloy we haven't seen yet I'm guessing), but the upgrade options are 18 or 19 inch M3 Competition alloys (the ones we see on the Valencia teaser car)..

How do you justify the 19s? I'm guessing the car would be slower with them on - what's the trade-off in benefit, more grip?

There is no real performance benefit with 19's that i can think of. If you want more grip you can just get a wider 18 inch wheel in order to house a wider tyre. The only other issue is brake clearance but i would imagine that an 18 inch wheel with low offsets would be big enough to house large discs and calipers.

But you gotta admit, it looks hot with 19's though and those flared guards. So i would go 19's simply for aesthetic reasons and sacrifice a little extra weight.

[BrokenVert]

The only thing that larger wheels do is reduce sidewall flex

[02fireman]

BMW engineers and drivers have claimed more than once that the M3 gets better times around the Ring with 18's, so if I get 19's it would be for purely visual reasons.

[IZAGLO]

Originally Posted by fly135

There is no real performance benefit with 19's that i can think of. If you want more grip you can just get a wider 18 inch wheel in order to house a wider tyre. The only other issue is brake clearance but i would imagine that an 18 inch wheel with low offsets would be big enough to house large discs and calipers.

But you gotta admit, it looks hot with 19's though and those flared guards. So i would go 19's simply for aesthetic reasons and sacrifice a little extra weight.

agreed^^^ The ONLY reason i am upgrading my rims to 19's is looks. And the SF71's i am buying are not offered in 18's. Yea, the car will be a hair slower, but with a JB3 or other tune the car is faster than i will ever need for a DD, it's almost toooo much for me at times....Also as Vert mentioned the "reduce sidewall flex" is something this car really needs if upgrading the rim/tire combo to non RFT's..

[Atropos]

Getting 19s instead of 18s = doing it wrong.

Same goes for lowering a car to the point that there's rubbing.

[Madozu]

Originally Posted by BrokenVert

The only thing that larger wheels do is reduce sidewall flex

+1 ... and this means better (more precise) steering feel.

On the other hand: the reduced wheelbase and the reduced weight compared to an E90 M3 could mean that the difference between 18s and 19s is minimal compared to an E90 M3.

[niuniu]

Originally Posted by Atropos

Getting 19s instead of 18s = doing it wrong.

Same goes for lowering a car to the point that there's rubbing.

Is this true or is it just more nonsense ' I think I know best na na' rhetoric?

Are M 'doing it wrong' when they have 19's on the 1M in Ascari etc?

[Atropos]

Originally Posted by niuniu

Is this true or is it just more nonsense ' I think I know best na na' rhetoric?

Are M 'doing it wrong' when they have 19's on the 1M in Ascari etc?

No rhetoric, just physics. Lighter = better, across the board. Larger rims can accomodate larger braking systems, which is always good, but in most cases cars that have 19" / 20" and up rims are doing so for aesthetic, not performance or brake system reasons.

[Guibo]

Less sidewall flex is desirable for turn-in crispness, particularly in a sequence of corners with many transient manuevers as you might find in an autocross. However, a surprising number of road tests indicate smaller wheels and larger sidewalls can actually improve steering feel, although these are not always same-tire comparisons. Taller sidewalls tend to be more progressive in slipping.
C&D did a pretty decent test by trying to eliminate manufacturer and model variables here:
http://www.caranddriver.com/features...sted-tech_dept


Keep in mind that Ascari is probably a much more ideal surface free of ruts and bumps than a real-world road. BMW will want to make a favorable first impression, and a car on big wheels has the right visual impact. None of the journalists was allowed to drive the car anyway, as I recall (could be wrong).

[fly135]

Hey guys, dont forget that although sidewall flex (of the tyre) may be a factor to consider, it has nothing to do with the size of the wheel. If you are worried about widewall flex and wheel weight just get 18's with lower profile tyres....problem solved. You dont have to have larger wheels to reduce the sidewall flex. Although going to a thinner sidewall without increasing wheel size will throw out the gearing a little.

I still think the 19's look the part though.....

[Ash83]

Originally Posted by 02fireman

BMW engineers and drivers have claimed more than once that the M3 gets better times around the Ring with 18's, so if I get 19's it would be for purely visual reasons.

+1

[Redline]

I'd go with 18inch

I always wonder why GTR is doing 20in. A waste in my oppinion.

[Tessio]

It's your car and a pretty personal choice. Myself, I'm always weighing the looks to performance ratio, it seems, when it comes to wheel/tire packages. I tend toward light weight but this car looks great on 19s.

19s don't have to be heavier than the stockers. You may find that a light 19 on lightweight non-runflats like PS2s or Hankook V12s is less weight than the stockers on runflats, which are pretty heavy. The weight on a 19 will be 1 inch further from the center, though how much that increases inertia in the real world, I don't know. As for ride, tramlining and response, I thought that even the M3 felt better and reacted quicker on 18's and PS2 tires, but if you keep it light, you might find no net loss over stock, maybe it'd be a push?

On a track the usual prescription is the shortest, lightest, widest you can fit, but even track setups are tricky and one of the black arts there is suspension tuning for a particular course.

Dropping down to LTW 17s on my e46 and fitting them with lightweight PS2s had the entire wheel assembly coming in at 37 lbs when the 18-inch ZHP package assemblies were 46-50 depending on tire choice. THAT was noticeable in that car in throttle response alone, especially from a dead stop. Not quite like increasing the diff ratio, but similar, if that makes sense. The car got uglier though

From a looks perspective, I think 19s are the perfect size for this car. I just like them. They seem more proportional to the huge wheel arches and tall sides of the car, so I'm torn myself on which way to go. As a previous poster noted, these things are pretty torquey, so even if the 19s you choose weigh more, you may not feel it, especially in an M.

It would be pretty cool to experiment on our own cars with different sizes at one of the regional BMWCCA tech events. Maybe just swap with others and do a test circuit to get a feel for them? That might even be cool for people who are considering a change to non-runflats to swap with someone on nons and have a test run. Even to swap rides with people with tunes and without and so on.

[spiderz17]

Originally Posted by maxnix

Then pray tell us why you are getting the performance version of an already high performing car?

Maybe because he wants to??

As Tessio already said, no one has to justify anything to anyone except themselves (and maybe a skeptical wife ).

[MinusS50]

I think what matter as some people say is the overall weight between the 18 and 19 inch wheels.

The rest is pointless the only thing which count is the unsprung weight

[MrRoboto]

Originally Posted by BrokenVert

The only thing that larger wheels do is reduce sidewall flex

Buy better tires.

[Muffnbluff]

Reasons why I wouldn't want 19s:

potholes
more expensive tires
harsher ride

[niuniu]

Originally Posted by Muffnbluff

Reasons why I wouldn't want 19s:

potholes
more expensive tires
harsher ride

How much harsher would a ride on 19s actually be over 18s?

I've never had a car with 19s before, so really have no idea what a daily driver would be like with them on.

[The1]

contrary to what a lot of people are led to believe, some sidewall flex is good. that's why i would stick with an 18. it allows for more control. and it also allows for better grip. when weight transfers over onto one wheel it has the ability to compress a bit and provide a slightly better contact patch. as minimal as this is, it can make the difference between a 4.7 and a 4.9 second 0-60 time, or save you 2 seconds around a medium sized track.

that being said, all the extra rubber that is put into the Run flat tires seems to act the same way as putting a wheel that's too big on a car, there's less flex over all and it skips around over bumps more because it can't absorb them, thus killing handling.

And seeing as M cars don't use run flats, you might be able to get away with 19"s as the run flat draw backs aren't there. it will have to be one of those things someone on the boards will have to experiment with. But seeing as the car would come with 18" and non run flats, i can't see their being any perfomance gain from a 19 at all. it's purely for asthetics.

I often wonder if the 18s are even too big for our cars.

if people have issues with what i'm saying, how come formula 1 doesn't use low profile tires. or even drag cars?

[Guibo]

Originally Posted by The1

if people have issues with what i'm saying, how come formula 1 doesn't use low profile tires. or even drag cars?

Probably because of regulations designed to keep the field even and constrain budgets. But I think there may be good technical reasons why that is in Formula One, for the reasons you cited.