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-   -   Adverse effects of upsizing rims and tires 2000 323i E46. (http://forum.e46fanatics.com/showthread.php?t=1008329)

bimmeupscotty 10-05-2013 08:13 PM

Adverse effects of upsizing rims and tires 2000 323i E46.
 
OK so I want to go bigger (225/40/18 45lbs) on the wheels (currently at stock 195/65/15... 40lbs), but I wonder how dramatic the effects will be when doing so. Things like burning up the tranny or breaks quicker, or creating extra work for the engine at low gear, and also the effects it has on the on-board computer (speedo, gear shifting ratio, ABS). My Bimmer has 148k so as of now its a finely tuned machine. Should I just keep it that way? Or obviously since there is some debate about this there is actually some truth behind it.

RockLee 10-05-2013 09:13 PM

The speedo might be off a little if the whole wheel is bigger or smaller than stock. (Please correct me if I am wrong.)

bimmeupscotty 10-05-2013 09:31 PM

Quote:

Originally Posted by RockLee (Post 15751489)
The speedo might be off a little if the whole wheel is bigger or smaller than stock. (Please correct me if I am wrong.)

Well I did the math and it says stock Vs. upsized will be off 0.28/ Mi per 65 mi. I don't think that's bad. I could be wrong tho. I'm not a NASA scientist. lol I guess I mainly wonder what it will do overall mechanically (engine and transmission/ differential wear). People tell me I'm a perfectionist. Maybe I'm over thinking it too much. IDK..........Opinions Welcomed.
:idea:

NumbaOneNewb 10-05-2013 09:33 PM

Re: Adverse effects of upsizing rims and tires 2000 323i E46.
 
Rock, you're correct. I usually drive at the fine line of speed limit, going above it by 8. Because I know the speedo is incorrect, i add in another 5 on top. When I had my 19s I only added the 8 plus maybe 2 on top.

Benefits of bigger rims: more than likely better than what you have on, looks better with a lowered car, more rubber width wise should equal better traction and handling if rims are within the limits of what your car can handle.

Negative: upkeep cost, tire replacement more frequent, more than likely unless you spend a fortune it'll be heavier and slow you down, more likely to be targeted for theft, easier to bend or damage rims

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NumbaOneNewb 10-05-2013 09:34 PM

Re: Adverse effects of upsizing rims and tires 2000 323i E46.
 
I would approve 18s with a lowered setup. Although 19s look way better the financial costs don't justify any of it. You'll be ok

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lszlszx 10-05-2013 09:34 PM

I believe the overall diameter is almost the same.
Weigh the stock wheel and do your research on the new ones.

Chances are they'll be heavier, but lightweight 18s may not actually weigh more than your stock rims.
Have your suspension been replaced? Wide, low ratio rim/tire combo may highlight weaknesses of a worn suspension.
In short, upsizing is OK if the overall diameter is the same.

bimmeupscotty 10-05-2013 09:48 PM

Quote:

Originally Posted by lszlszx (Post 15751521)
I believe the overall diameter is almost the same.
Weigh the stock wheel and do your research on the new ones.

Chances are they'll be heavier, but lightweight 18s may not actually weigh more than your stock rims.
Have your suspension been replaced? Wide, low ratio rim/tire combo may highlight weaknesses of a worn suspension.
In short, upsizing is OK if the overall diameter is the same.

Edited original post. Stock 15's weigh 40lbs. and 18's weigh 45lbs. Thinking that's the equivalent of a bowling ball on each corner. Is 20lbs difference all that much? 20lbs Weight distribution on all fours is better than a fatty in the passenger seat. lmao

Seriously tho, there is no new suspension. That will be next. Possibly after disc break upgrade. Depending on the feel with the new wheels. I'm OK with the look of how it sits right now. They're BMW after market 18's from a '99 7 series. Post pics soon!

lszlszx 10-05-2013 09:53 PM

5lbs. isn't bad, considering the 18s are probably a lot wider.

TitaniumCranium 10-05-2013 10:12 PM

The weight difference may literally be the equivalent of a bowling ball on each corner but where the weight is makes a world of difference. This is unsprung weight and the effect is dramatic on how the car rides, handles, and accelerates.

The heavier the unsprung weight the slower a wheel assembly is to rebound from a sudden change in surface. It's slower to respond to acceleration from the drive train also. These aren't simply mathematical differences, they're noticeable. Do a little research on the effects of added unsprung weight.

17" BMW sport wheels come in at around 18# per wheel, some of the lightest BMW wheels out there. If you're driving a 325 I would pay attention to wheel weight if you're trying to get some sportiness out of the car. If all you're after is what you think looks cool then it doesn't really matter. Up to you.

bimmeupscotty 10-05-2013 10:40 PM

Quote:

Originally Posted by TitaniumCranium (Post 15751561)
The weight difference may literally be the equivalent of a bowling ball on each corner but where the weight is makes a world of difference. This is unsprung weight and the effect is dramatic on how the car rides, handles, and accelerates.

The heavier the unsprung weight the slower a wheel assembly is to rebound from a sudden change in surface. It's slower to respond to acceleration from the drive train also. These aren't simply mathematical differences, they're noticeable. Do a little research on the effects of added unsprung weight.

17" BMW sport wheels come in at around 18# per wheel, some of the lightest BMW wheels out there. If you're driving a 325 I would pay attention to wheel weight if you're trying to get some sportiness out of the car. If all you're after is what you think looks cool then it doesn't really matter. Up to you.

Very True. I will look into unsprung weight for sure. Thanks for the reply! Everyone on this topic has been awesome! Its a big deal issue. I love the way the BMW handles right now and drives overall. Wouldn't trade it for anything but another BMW. Def want to make sure I don't destroy it by adding extras to it.:bump:

ThePointman 10-05-2013 11:27 PM

I have upsized Axis Penta staggered wheels with low profile (Band-Aid, lol) tires and it drives\handles amazing. I do feel allot more feedback from the road with the low profile tires but it's well worth it. The speedo is only out by a couple of Km and it looks awesome with the stance. Couldn't be happier.

TitaniumCranium 10-05-2013 11:36 PM

Something else to consider here is that when the rim size increases the amount of rubber decreases. I've read, but don't have any factual information to back it up at this point, that rubber weighs more than aluminium. If that is true, a larger lightweight aluminum wheel should have a notable effect. It would be worth looking up the weights of the tires too, if there is somewhere that they're published. It's all a balancing act.

Marshmallow 10-05-2013 11:42 PM

Adverse effects of upsizing rims and tires 2000 323i E46.
 
I think if they are sic wheels then they are fine either way.

bimmeupscotty 10-06-2013 01:26 AM

Quote:

Originally Posted by ThePointman (Post 15751649)
I have upsized Axis Penta staggered wheels with low profile (Band-Aid, lol) tires and it drives\handles amazing. I do feel allot more feedback from the road with the low profile tires but it's well worth it. The speedo is only out by a couple of Km and it looks awesome with the stance. Couldn't be happier.

How long have you had it? Have you noticed any slipping of the transmission, burning more oil from the engine, or noticeable difference in the breaking system?

Solidjake 10-06-2013 06:08 AM

From 15's to 18's it will be a massive difference. The ride will instantly become a lot harsher. Your handling will improve but at the cost of comfort depending on your roads.

bimmeupscotty 10-06-2013 02:09 PM

Quote:

Originally Posted by Solidjake (Post 15751938)
From 15's to 18's it will be a massive difference. The ride will instantly become a lot harsher. Your handling will improve but at the cost of comfort depending on your roads.

For sure! I looked up "Unsprung Mass" and read all about the weight factor that goes into the jounce of suspension. Fortunately for me the roads are kept well in AZ, no ice, snow, salt, rain to deal with. The biggest natural issues we have out here is the rubber parts drying out and breaking constantly because of the heat and sun. Ive got it in the garage now tho so its not a big problem. I think I will upsize and try it out. If I cant handle the effects I will just go back to the stock set I have on deck. Everyone seems to say it wont change things too much other than the suspension (if i keep the diameter of the wheels the same). The roads out here really are like glass for the most part. :clap: Mathematical Equation
http://static.pepboys.com/images/car...er_example.gif

Solidjake 10-06-2013 02:25 PM

Funny thing is on my NY to LA run I got my flat tire in AZ :rofl:

bimmeupscotty 10-06-2013 04:02 PM

Quote:

Originally Posted by Solidjake (Post 15752546)
Funny thing is on my NY to LA run I got my flat tire in AZ :rofl:

Purple Heart Trail (I-40)? alot of truckers use that highway between New Mexico, Northern AZ, Las Vegas, and Los Angeles.

Solidjake 10-07-2013 03:45 AM

Yup I-40 :thumbup:

Click on my cross country link under my sig if you have time

VMRWheels 10-07-2013 12:47 PM

You shouldn't notice any major difference in maintenance or possible parts failures. I would say you would notice a difference in ride quality though.


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