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[Sfapsey]

My M3 has 19" wheels and I would like to get some new wheels. I am considering going with 18" wheels. Anyone have any experience with the two wheels sizes with respect to handling, look and ride? The roads around here are a bit rough and I have already destroyed one set of tires hitting a pot hole. I am hoping the extra side wall of a 18" tire will be more forgiving. I'm also getting tired of the skinny tire look.

[gblansten]

Wrong forum. Go to the wheels and tires forum. There are lots of great threads on this and other related issues.

Like this one: http://www.m3post.com/forums/showthread.php?t=145741

And this one: http://www.m3post.com/forums/showthread.php?t=522028

Here is the forum: http://www.m3post.com/forums/forumdisplay.php?f=119

[1MOREMOD]

i have almost identical looking 18 and 19 wheels and like the asthetics of the 19s better. the spokes look better a litle longer and the thicker sidewall doesnt look as good but i am also getting used to the 18s as they look more purposeful and do provide better protection with their taller sidewall. 18s are lighter generally and allow wider tire so can offer better performance as well.

[davesaddiction]

I've got the OEM 19s (not comp. pkg.) and the stock 18s (winter set), and while the 19s look much better, the car does feel more "chuckable" to me with the 18s on.

[Rk-d]

Originally Posted by Sfapsey

My M3 has 19" wheels and I would like to get some new wheels. I am considering going with 18" wheels. Anyone have any experience with the two wheels sizes with respect to handling, look and ride? The roads around here are a bit rough and I have already destroyed one set of tires hitting a pot hole. I am hoping the extra side wall of a 18" tire will be more forgiving. I'm also getting tired of the skinny tire look.

Went from OEM 18/PS2 to ZCP 19/PSS. Cornering was clearly better, which is probably a combination of tire and sidewall stiffness. The 18s may have been a hair quicker off the line, but nothing that I really notice. Ride difference is negligible. Personally, I think the 19s look a lot better - going from 219m to 19 inch ZCP really changed the look of the car - more aggressive.

[M3takesNYC]

Originally Posted by 1MOREMOD

i have almost identical looking 18 and 19 wheels and like the asthetics of the 19s better. the spokes look better a litle longer and the thicker sidewall doesnt look as good but i am also getting used to the 18s as they look more purposeful and do provide better protection with their taller sidewall. 18s are lighter generally and allow wider tire so can offer better performance as well.

Any savings in actual wheel weight is drastically offset by the significantly increased mass of the thicker tire side-walls which is at the absolute worst place for added weight on a rotational setup which is near the edges. A few less pounds focused closer to the middle has negligible difference.

Depends on the tire, some do a good job of making their 18 inch tires as light as the less-sidewall 19s and in that case the lower wheel weight is taken advantage

For our cars you actually have an overall negative impact on acceleration given you are adding 2 pounds per tire at the most distant surface for going from an 18 to 19 inch wheel. (265/40/18 weigh 27 pounds and 265/35/19 weight 25 pounds) Our 245 front tires are more equal in the two sizes so not as much of a problem

So you look at two metrics-

Unsprung weight change-to benefit by going to an 18 the wheel would have to be atleast lighter than the 19 by more than 2 pounds as it has to carry a 2 pound heavier tire

Rotational weight difference-given its carrying to more pounds on the outermost place away from the center of the rotational mass, than you would need to significantly drop mass on an 18 inch tire near the center to make up for 2 extra pounds at its outside. The force to rotate 2 extra pounds sitting way on the outside is probably along the lines of 6-10 pounds near the center.

So really just to break even for performance comparing our 19 inch setup, you need to find wheels that weight atleast 6-10 pounds less and than still make sure you are going with the same brand of tire or a brand that does not add even more weight to the outside. Here is the rack site for the tire weights

http://www.tirerack.com/tires/tires....ilot+Sport+PS2

[1MOREMOD]

i saved 6lbs per corner and tire 1lb lighter so made difference.

[M3takesNYC]

But was your savings at the center or was the tire you had to used given thicker side-wall as light? Can you post which tires you used as its a rarity to find a higher sidewall lighter than its smaller side-walled 1 plus sized tire.

Would be good info for people looking for tires to swap onto 18s so they do not fall victim to lowering wheel weight but increasing tire weight which leads to worse performance

[M3takesNYC]

Actually did not see your sig. Funny nitto weights are not listed on their site nor can I find them anymore.

Did you ever weight the tire itself? Just curious

[1MOREMOD]

yes my wheels are 22 and tires 26 so weigh more that ps2s which most tires do. so set up is 48 but comparing to my vmr boat anchors not oem.

[LarThaL]

Originally Posted by M3takesNYC

Any savings in actual wheel weight is drastically offset by the significantly increased mass of the thicker tire side-walls which is at the absolute worst place for added weight on a rotational setup which is near the edges. A few less pounds focused closer to the middle has negligible difference.

Depends on the tire, some do a good job of making their 18 inch tires as light as the less-sidewall 19s and in that case the lower wheel weight is taken advantage

For our cars you actually have an overall negative impact on acceleration given you are adding 2 pounds per tire at the most distant surface for going from an 18 to 19 inch wheel. (265/40/18 weigh 27 pounds and 265/35/19 weight 25 pounds) Our 245 front tires are more equal in the two sizes so not as much of a problem

So you look at two metrics-

Unsprung weight change-to benefit by going to an 18 the wheel would have to be atleast lighter than the 19 by more than 2 pounds as it has to carry a 2 pound heavier tire

Rotational weight difference-given its carrying to more pounds on the outermost place away from the center of the rotational mass, than you would need to significantly drop mass on an 18 inch tire near the center to make up for 2 extra pounds at its outside. The force to rotate 2 extra pounds sitting way on the outside is probably along the lines of 6-10 pounds near the center.

So really just to break even for performance comparing our 19 inch setup, you need to find wheels that weight atleast 6-10 pounds less and than still make sure you are going with the same brand of tire or a brand that does not add even more weight to the outside. Here is the rack site for the tire weights

http://www.tirerack.com/tires/tires....ilot+Sport+PS2

Give this man a gold star !!! People focus so much on absolute wheel weight, but as you correctly pointed out, it is tire weight that is more important due to the location of the weight!!! Same with wheel design itself. A wheel where the spokes are thicker towards the rim will generate greater undesired rotational forces than one with more of the mass concentrated near the hub.

[gatorfast]

18s will be noticeably more comfortable of a ride than 19s

[bimdo]

a classic way to illustrate the effect of where the weight is located,how far from the center, is to think of a figure skater spinning with arms extended.when they pull their arms in close to their body,they spin dramatically faster.there's then less rotational mass far from the center,and so less force is needed to spin it.

[VMcV3y]

Originally Posted by gatorfast

18s will be noticeably more comfortable of a ride than 19s

Originally Posted by Team Plutonium

for looks 19's... for tracking 18's all day long.

This is exactly my experiences with both sets/sizes over the last several weeks.

- V

.

[M3takesNYC]

Originally Posted by 1MOREMOD

yes my wheels are 22 and tires 26 so weigh more that ps2s which most tires do. so set up is 48 but comparing to my vmr boat anchors not oem.

The fact your tires weight more as I pointed out will give you a drop in performance. Comfort is improved but rotational weight is now worse than before likely even though you dropped pounds on the wheels. with 22 pound wheels and a tire that is a couple pounds more, its probably close to a wash.

Unsprung weight wise, the overall weight matters so braking and cornering may be slightly improved with a net weight loss regardless of where the weight is but even this is not correct as the wheel/tire is spinning and therefore effects on rotational weight still come into play for cornering/handling.

Probably in your case though it is complete wash for performance so if others considering 18s with heavier tires, I would go for it if you want comfort or looks (if 18s appeal to you) but for performance make sure you get tires as light as the OEM you are replacing otherwise any wheel weight savings is totally gone to waste

[1MOREMOD]

not comparing to OEM tires as stated once again. ps2 are crap for anything but wet track use. michelins are super light because of soft sidewall construction which is worse than using 100lb tires. getting a super light weight tire provides no benefit if it cant handle the tasks assigned to it and makes arguments about rotational mass worthless. would you rather have a 23 lb ps2 and slide into the woods because 2 laps creates a greasy tire that needs cool down or one that can handle sustained operation at much higher temps and gets better when this happens?

[ms372]

Originally Posted by Team Plutonium

for looks 19's... for tracking 18's all day long.

+1
19's for the street 18's for the track and 20's don't belong on an m3

[e1000]

Originally Posted by M3takesNYC

Any savings in actual wheel weight is drastically offset by the significantly increased mass of the thicker tire side-walls which is at the absolute worst place for added weight on a rotational setup which is near the edges. A few less pounds focused closer to the middle has negligible difference.

Depends on the tire, some do a good job of making their 18 inch tires as light as the less-sidewall 19s and in that case the lower wheel weight is taken advantage

For our cars you actually have an overall negative impact on acceleration given you are adding 2 pounds per tire at the most distant surface for going from an 18 to 19 inch wheel. (265/40/18 weigh 27 pounds and 265/35/19 weight 25 pounds) Our 245 front tires are more equal in the two sizes so not as much of a problem

So you look at two metrics-

Unsprung weight change-to benefit by going to an 18 the wheel would have to be atleast lighter than the 19 by more than 2 pounds as it has to carry a 2 pound heavier tire

Rotational weight difference-given its carrying to more pounds on the outermost place away from the center of the rotational mass, than you would need to significantly drop mass on an 18 inch tire near the center to make up for 2 extra pounds at its outside. The force to rotate 2 extra pounds sitting way on the outside is probably along the lines of 6-10 pounds near the center.

So really just to break even for performance comparing our 19 inch setup, you need to find wheels that weight atleast 6-10 pounds less and than still make sure you are going with the same brand of tire or a brand that does not add even more weight to the outside. Here is the rack site for the tire weights

http://www.tirerack.com/tires/tires....ilot+Sport+PS2

The only problem with your analysis is that a lot of the weight of a wheel, far more than the difference the size of the spokes (or tire sidewall) weigh, is the barrel of the wheel, which is closer and smaller with a 18" wheel vs a 19" wheel. Yes the weight of an 18" tire may be slightly more, but if you keep the overall diameter of the tire the same, the heaviest part of the tire is still the tread and is the same unless you go significantly wider.

With that said, for a road car this argument is a bit silly. 18" wheels and tires will give you slightly more sidewall and a slightly more forgiving ride.

[M3takesNYC]

Originally Posted by 1MOREMOD

not comparing to OEM tires as stated once again. ps2 are crap for anything but wet track use. michelins are super light because of soft sidewall construction which is worse than using 100lb tires. getting a super light weight tire provides no benefit if it cant handle the tasks assigned to it and makes arguments about rotational mass worthless. would you rather have a 23 lb ps2 and slide into the woods because 2 laps creates a greasy tire that needs cool down or one that can handle sustained operation at much higher temps and gets better when this happens?

I had not heard the PSS was crap at the track. PSS are the same weight as PS2's but apparently you know better than I so not arguing there. Of course a premise has to be they are useable at the situation you need to use them or else of course the weight is of no value at all!

But in order to compare 18s vs 19s in general you have to compare it to what you are replacing so in this case the OEM 19's. Although you may not be inflicted by the problem, I do think people should be aware that if they go with an 18inch wheel and it is lighter, to be aware not to put a heavier tire on if there is lighter available with same abilities. A lot of people don't look at tire weight and hyperfocus on wheel weight.

As to the barrel being smaller on 18's means the weight is even less significant. Mass in the center has virtually no impact on rotational performance. Damping and handling will benefit but not speed or acceleration

[1MOREMOD]

i said ps2 is crap. it will only suffice for a beginning driver on a relatively stock car. pss is better but still not all that great. once speed increases even purpose built track tires like ad08s and no05s will start to chunk and go away on you in a very short number of laps. i am by no means an expert and already am exposing weaknesses of performance tires. i can back off and drive at the limit of my tires instead of my limit to keep the car together.

[slicer]

Originally Posted by M3takesNYC

As to the barrel being smaller on 18's means the weight is even less significant. Mass in the center has virtually no impact on rotational performance. Damping and handling will benefit but not speed or acceleration

Since when are barrels of the wheel located near the center? I agree that an 18" barrel is located more towards the center than a 19" barrel... But the barrel is a significant component of rotational inertia. On a 19" that weight is further outward where it has a larger impact. Plus it will weigh more than an 18" barrel.

And.... What about the impacts of a reduction in unsprung weight by going with 18's? apples to apples an 18" wheel tire will typically be lighter than a 19" wheel and tire (assuming same wheel and tire used for both). My research says lower unsprung weight improves handling.

I think we are splitting hairs with some of this but is an interesting discussion.