128i upgrade to 18” wheels

[Fenbers]

I want to put the 135i’s wheels on my 128i for the more aggressive look than anything else. I would slap on summer tires on the 18” wheels and mount my stock 17” wheels for the Winter. The stock 17” rims are narrower than the 18” rims standard on the 135i. Are their any reasons I would be advised not to do this aside from cost??

[chris_flies]

Nope. Wider usually equals more grip, and grip is a good thing. The Style 313 wheels (that's the BMW lingo for them) were optional BMW Performance Parta you could get from a dealer.

[Esteban]

Originally Posted by chris_flies

Nope. Wider usually equals more grip, and grip is a good thing. The Style 313 wheels (that's the BMW lingo for them) were optional BMW Performance Parta you could get from a dealer.

I believe the Performance 313 rears are NLA. Not sure but I think you can still get the 313M wheels (front and rear) that come on the 135is, but they're much more expensive than the Performance versions.

[Fenbers]

I expected to hear that one reason this would not be advisable is that the wider wheels would reduce my acceleration because the wheels are heavier, no??

[MrKevinRosales]

I think he's talking about the regular 1358 wheels, ie. Style 261 or 264, and worded it as the 135i's not 135is.

Either way if cost is not an issue go for it, no real downsides that I know of

[chris_flies]

Originally Posted by Fenbers

I expected to hear that one reason this would not be advisable is that the wider wheels would reduce my acceleration because the wheels are heavier, no??

Not really. The benefits of a little additional grip offset the costs of extra weight.

[Fenbers]

This is all great info, even if the nature of the question just seeks opinions! Very helpful! Sadly, I needed to spend my wheel cash on some medical issues. Need to save up again!

[Gangplank]

Originally Posted by Fenbers

This is all great info, even if the nature of the question just seeks opinions! Very helpful! Sadly, I needed to spend my wheel cash on some medical issues. Need to save up again!

Been there 2x or more. Once even had the new Apex wheels in a box shipped to my door & has to sell em for that same reason.

[nachob]

Originally Posted by Fenbers

I want to put the 135i’s wheels on my 128i for the more aggressive look than anything else. I would slap on summer tires on the 18” wheels and mount my stock 17” wheels for the Winter. The stock 17” rims are narrower than the 18” rims standard on the 135i. Are their any reasons I would be advised not to do this aside from cost??

you are smart to ask young Fenbers. Kudos to you for being inquisitive about this! I saw the post before me that simply states, yes wider equals more traction so better. However, that is only partially true and can be incorrect in some cases.

Firstly, Engineering. Idiots did not design the 128i. They didn't pull things out if their butt and throw darts at a board and say..hey Those wheels look like flowers so lets put those on the 128i. That car was designed by career automotive engineers in Munich and other parts of Germany that look at all aspects of the car.

Power: The 135i is turbocharged and has a lot of torque. The 128i has to rev to make it's power. The easier and quicker it revs, the more power you make quicker. A heavier wheel will affect your power delivery and make the car feel less alive. you will incorrectly assume that the reason you can't break the tires loose is simply more traction, but that is not the whole story. Since your NA car requires revs to make torque, it will not have the torque low to get a heavier wheel spinning. There is a sweet spot when you increase the wheel diameter and width where the gains in traction offset reduced performance. I feel that in the 128i, the 17s are the sweet spot due to it's normally aspirated nature where revving quickly is vital to make torque. If you go to an 18", you should take great pains to go with a very light wheel like a forged BBS RGR, or some other super lightweight wheel. Going to a 135i original equipment wheel will probably not be worth it. Here is a car and driver article on wheel sizes you should read:

Car and Driver Test on different Wheel sizes

Supension: Despite what you see and hear from the masses that are constantly going for bigger wheels and thinner tires, this is for looks. If you look at real race cars, they opt of a super stiff suspension with more sidewall. The sidewall is left to absorb road imperfections. Go look at a formula one car or Indy car and guess what...the ultimate race car has sidewalls!



In the current show over go culture, the suspensions are softened so you can run run-flat and low profile tires. So in the case of the 128i, your suspension was calibrated for run-flats so it should be compliant enough to go plus 1. But if your suspension was an M-Technic that was tuned for for non-runflats, you will find extra harshness. Personally I like my suspensions firm but the reality is that our car interiors are all plastic and this harshness will manifest itself in your interior falling apart, creaking, rattling plastic everywhere. Ifyou live in places like Utah, South Dakota that have beautiful new roads, it's OK but if you live in SoCal where our roads make the lunar landscape look like golf green, then take that into account.



Braking Dynamics: The heavier wheel and tire combination saps more power to get it rolling and conversely it takes more braking power to stop it's rotational inertia. Your 128i has little brakes which are awesome because it makes the car lighter and it has to stop a lighter car with lighter tire/wheel combination. Don't understimate the rotational forces of a heavier wheel. Try spinning a lightwheel tire and wheel and stop it with your hands. The take a tire and wheel combination that weighs more and repeat. Your braking performance can be impacted as well as heat build up due to heavier rotational inertia.

Fun: My first BMW was 2004 325i 5 speed. I remember taking it on spirited drives and the rear would break loose gently and I felt a rally driver on these back roads. I would drop the clutch and the rear would chirp on it's stock Bridgestone Turanza all season tires. I loved it! Then of course I wanted the stickiest tires possible and I replaced it with a set of Micheline Pilot super sports with side BBS RX wheels. I then hit my favorite back road and the traction was amazing. The Supersports never let go. I tried sidestepping the clutch and there was no more chirp, but the little 2.5 liter motor bogged down. I took my favorite corner and felt more g forces but there was no more tail out action, no more breaking the tires loose. I now could go faster on a rural road that was probably safe without drama. Then it hit me. I could no longer break the rear loose in the dry. I could no longer get the rear to kick out unless I did something very fast and dramatic. I looked out over what I had created and it was not good. I was dissapointed now because I was not driving for lap time, I was driving for fun and excitement and I missed the old stock Turanzas. They were a better fit for the low power 325i.

So if you don't live in SoCal where the roads are horrible and you have the stock run-flat tuned suspension and you want to go to a bigger wheel for looks, then you should get a different wheel and tire combination that weighs no more than your stock 17" setup.


There are plenty of cool lightweigh wheels out there from BBS, Enkei and even APEX. Personally, the BBS RGR is super light. The cheaper BBS wheels like the RS, CHR etc are heavy and cast. You want a lighter wheel.

You can get tire weights from Tire Rack. Get the size and brand of your tire and add it to the weight of your stock wheel which is posted online already.

Then get the weights of your new wheels and add the tire weights. your goal should be to not add any weight.

Finally, if you go with stock 18s but use non-runflat tires, the weight savings of the non-runflat might offset the bigger wheel but you have no spare, so you have to think about that.

personally, i would go non-runflat because they are more compliant than runflats, lighter, cheaper and compliance is good when going with less sidewall.

I hope that helps. I know the guy that gave you the simple answer like side wheel = more traction seems more appealing but real life is never really that simple. I hope that helps.

[gjm120]

Originally Posted by nachob

you are smart to ask young Fenbers. I hope that helps.

Am I going crazy or wasn't there a political reference in there at first? Thanks for pulling it out if so. Coming in here after visits in the politics subforum is refreshing.

Good answer. I'm kind of sold on keeping 17" wheels on my car especially with a fairly stiff suspension. Downside is brake upgrades are limited but not a consideration for me

[nachob]

Originally Posted by gjm120

Am I going crazy or wasn't there a political reference in there at first? Thanks for pulling it out if so. Coming in here after visits in the politics subforum is refreshing.

Good answer. I'm kind of sold on keeping 17" wheels on my car especially with a fairly stiff suspension. Downside is brake upgrades are limited but not a consideration for me

Yes, it came out in stream of consciousness style, then I realized that it might detract from the message so I replaced it with an apolitical term.

Kidding aside, It really did just come out but yes, better leave politics out of it. We need less of that!

Noted and done : )

[sixburgh]

when changing the geometry of wheels, suspension, etc. on a BMW, you entertain a slippery slope.

[nachob]

Originally Posted by sixburgh

when changing the geometry of wheels, suspension, etc. on a BMW, you entertain a slippery slope.

Great point I forgot if you go aftermarket get the correct offsets too!

[MAMSport]

When I went to BMW performance 18" wheels, I noticed that the rear suspension would get 'rubber band-y'. I'd guess the extra traction from wider rubber allowed more load into the rear trailing arm bushings (my car has M3 suspension pieces front and rear). My consideration is to replace these with the M3 parts at some point in the near future. At this time, I'm ready to sell these wheels - BMW style 182 for 135i with proper offset and with gloss black finish. PM for additional pics - they are too large to fit as attachments. Or, help me to resize the images so that I can post them.

Image:

[elitesales305]

i went from 17 square to 18 264... acceleration was noticibly reduced.. but when coasting the wheels are heavier thus traveling further without having to hit the right pedal..
if you do mostly street iner city driving .. ur gonna hate it.. if on the expressway.. mehhhh not so much of a pain..
also, fyi
wich from the posts I read no one touched on.. your speedo will be off!!!!!

[crowtrobot]

FWIW I went to 18" EC7s after hemming and hawing on this subject, and was happy that I did. The overall weight was reduced (18" 235/40 are about the same weight as the 225/45s I was running previously, and the tires were ~3lb less per corner).

The stock wheels I have with 205 section tires feel a little more nimble on the street, but the cornering ability with the 18's and 235s is worth it to me. I cut my lap times dramatically vs. the 225s. Really depends on what you want to do with it. If I wasn't tracking the car, I'd probably just stick with the stock 17's.

[Tommm]

I have 16x7 rims from a Z3 on my 128i with 225 wide tires for the track. The tires currently on those rims are 25" in diameter (they had 200 miles on them when we blew the motor of the 944S at the track). The next set will be on the 16" rims with tires that are 225 in width and a smaller diameter. Shave an inch in diameter and I lowered the center of gravity 1/2" for "free" and kept my street suspension stock.

[duder13]

FYI, here's a pretty sweet deal on 313s. Caveat emptor.

https://www.ebay.com/itm/BMW-E82-E88...kAAOxyPLpRfNDA

[Esteban]

Originally Posted by duder13

FYI, here's a pretty sweet deal on 313s. Caveat emptor.

https://www.ebay.com/itm/BMW-E82-E88...kAAOxyPLpRfNDA

Was hoping these included the discontinued rear Performance 313s (18x8.5, P/N 36116787646) but they are only the fronts (18x7.5, P/N 36116787645). Might've bought this set for myself as extras, mostly for the rears though since they are NLA and would fit my staggered set-up. Don't want 4 extra front wheels, but maybe someone does. I imagine they'll be discontinued sometime in the near future as well.

PS - I do have 1 extra front, although it's scratched (by dealer, they paid for a new one). Still in good shape and will be used as my spare.

[duder13]

Originally Posted by Esteban

Was hoping these included the discontinued rear Performance 313s (18x8.5, P/N 36116787646) but they are only the fronts (18x7.5, P/N 36116787645). Might've bought this set for myself as extras, mostly for the rears though since they are NLA and would fit my staggered set-up. Don't want 4 extra front wheels, but maybe someone does. I imagine they'll be discontinued sometime in the near future as well.

PS - I do have 1 extra front, although it's scratched (by dealer, they paid for a new one). Still in good shape and will be used as my spare.

Ah, you’re right. Looks like sets of all four go for closer to $2k.

[Esteban]

Originally Posted by duder13

Ah, you're right. Looks like sets of all four go for closer to $2k.

Yeah, except you can't get the Performance 313 rears anymore. As I said above, they're discontinued. You can however still buy the 313M wheels: front - P/N 36116856666, rear - P/N 36116856667, which is probably what you are referring to. These are the same wheels that come on the 135is. Almost twice the price of the Performance versions but at least they're still available, front and rear. I have the Performance versions on my car.

[duder13]

Originally Posted by Esteban

Yeah, except you can't get the Performance 313 rears anymore. As I said above, they're discontinued. You can however still buy the 313M wheels: front - P/N 36116856666, rear - P/N 36116856667, which is probably what you are referring to. These are the same wheels that come on the 135is. Almost twice the price of the Performance versions but at least they're still available, front and rear. I have the Performance versions on my car.

Gotcha, I wasn't differentiating between the M and Performance visions. Are they identical, outside of the little M badge?

This seems like a good deal for the M versions: https://www.ebay.com/itm/BMW-OEM-E81...QAAOSwPDVbzio9