BMW style 312 wheels on a GT?

Does anyone have BMW style 312 20" wheels in silver or Ferrite Gray on a GT? Wondering how the Ferrite Gray would look with DSBM?

Would really like some pictures.

TIA!

bryan...
see if you can find a dealer that has a 5 series sedan with 20's before you pull the trigger... my buddy put 20's on his 535gt and is not loving the ride as much as he did with 19s... he's going back to 19s... not sure what his plans are for his 20's when he switches and they are not 312s.....
mp

Originally Posted by mpress

bryan...
see if you can find a dealer that has a 5 series sedan with 20's before you pull the trigger... my buddy put 20's on his 535gt and is not loving the ride as much as he did with 19s... he's going back to 19s... not sure what his plans are for his 20's when he switches and they are not 312s.....
mp

Good point MP! Since we have base 18s now, I wonder if it would be like riding around in sport or sport+ by upgrading to 20s.

Having just traded in a car with very low-profile tires that produced a garage full of bent/cracked rims and tires with bubbles, may I suggest either sticking with 19" or if you go with 20", getting the Tire & Wheel Insurance Plan? Cracked/bent rims can be a major crimp in your lifestyle.

I'm very happy with my 19" 302's - they are all-season to boot.

Edited to Add: I just check BMWUSA.com and it looks like the 312's are 21" rims??

Originally Posted by starryeyed

Having just traded in a car with very low-profile tires that produced a garage full of bent/cracked rims and tires with bubbles, may I suggest either sticking with 19" or if you go with 20", getting the Tire & Wheel Insurance Plan? Cracked/bent rims can be a major crimp in your lifestyle.

I'm very happy with my 19" 302's - they are all-season to boot.

Edited to Add: I just check BMWUSA.com and it looks like the 312's are 21" rims??

I live in Atlanta, if I lived up north I would stick with the 18s.

They come in 20 and 21".

Sent from my PG86100 using Bimmer App

Hey Bryan, I'm also looking into bumping up from 18's to 20's and am wondering what that does to ride comfort and performance.

My 535GT has 18x8.0 with 245/50 size tires all around and they look too blah for me but I like the ride comfort. I tried to upgrade as part of the order but could not since it was an ED. I am looking at ordering a staggered 20" configuration with Conti DWS 245/35r fronts and 275/35r rears (suggested by the retailer). Does anyone know what aspect ratio I can put on 20"s without affecting my current ride comfort and performance?

Here are the wheels I am deciding between:

Vossen CV1:


Vossen CV3:

Originally Posted by gmblack3

I live in Atlanta, if I lived up north I would stick with the 18s.

They come in 20 and 21".

Sent from my PG86100 using Bimmer App

They are beautiful, that's for sure. So are the ones posted by mycabrandz - WOW. Please post pictures if you decide to switch!

If you want to maintain the comfort, don't get thinner (lower profile) tires by going to larger wheels. Personally, I can't see them while I'm driving, and don't stare at my car...I'm beyond what other people think where it affects me. While you might not get freeze/thaw generated potholes, there's lots of other things that generate road hazards, then, what happens if you do take the thing on a long road trip? Only if I used the vehicle on a track would it make sense to me, but the GT isn't exactly the kind of car whree that's a wise option, at least if you wanted a chance to win.

first, i want to apologize to Bryan for hijacking his thread. I hope you find someone with 312's in 20 suited up on a DSB GT. I posted a thumbs up for you when you shared your ED pics. Looking forward to seeing more pics with the 312 if you decide to go that route.

If you want to maintain the comfort, don't get thinner (lower profile) tires by going to larger wheels.

@jadnashuanh: I should rephrase the question then: Can i get 20's with higher aspect ratio allowed by the GT's dimensions where it would be similar in ride comfort as the 18's? I'm not keen on sizing wheels and tires so this is why I am asking. None of the retailers I've contacted seem to know, just want to sell the recommended configuration, and explained that going outside of that would be at my own risk. Hence my puzzlement since the sidewalls I would prefer are of greater depth, would provide better comfort (right?), and can take more impact on rough roads.

I have an opportunity to offload my current wheels at a decent price and getting a good deal on the new ones so this is why I am considering the upgrade.

First thing you need to understand takes a little bit of math...pretty much any vehicle is designed with a specific rolling diameter. If you change the overall diameter, you change the number or revolutions/mile and the gear ratios. That means that the odometer and speedometer no longer read correctly, and that's if the wheel will actually fit at all without rubbing on something either while going straight or with the wheel at full lock (or getting there!), then throw in hitting a bump.

The hassle in trying to figure overall diameter is the wheel is in inches, and the tires are metric, thus the math (it's not hard, though).

Take the stock 245/50-18" tire. To figure the sidewall height you need to understand what those numbers mean. The first number indicates the total width in mm. The second number is the ratio of the width to height. In this instance, the height of the sidewall is 50% or 1/2 of the width. Since the total tire diameter includes the tire on both sides, this one is easy, each is 1/2 of the width, so x2, the height of the tire is 245mm. mm->inches 245/25.4=9.65" (approximately) So, then add the tire height to the wheel and you get a wheel/tire assembly = 27.65".

Any tire you use, when mounted on the wheel should be very close to that diameter...any difference means that the odometer/speedometer/clearance may become an issue. If you change the wheel diameter, you'd need a lower-aspect tire to maintain the same diameter. So, maybe go to 275/30-21, you'll notice that the tire height is now only 30% of the width. The tire is about 3.25" x 2 or 6.25". Now, add that to the 21" wheel, and it becomes 27.25". Close to the overall diameter of the stock wheel. Normally, I'd like it to be closer, but you get what you get...they don't make tires in all sizes. The difference is about 1.45%. You'd have slightly faster accelleration, but you'd actually get that many less miles before your warranty expired! verses the stock (your odometer would read more miles than you actually drove if you kept the stock tires/wheels).

If you run the numbers for the stock tire/wheel combinations, each one will be very close to that number. Deviating from that diameter risks interference and miscalibration and should be avoided. It used to be you could change the gear on the odometer and compensate...don't think they'll let you do that with the primarily computer generated stuff - i.e., I don't think you have access to the computer code required to change this.

[QUOTE=mycabrandz;6738658]Hey Bryan, I'm also looking into bumping up from 18's to 20's and am wondering what that does to ride comfort and performance.

My 535GT has 18x8.0 with 245/50 size tires all around and they look too blah for me but I like the ride comfort. I tried to upgrade as part of the order but could not since it was an ED. I am looking at ordering a staggered 20" configuration with Conti DWS 245/35r fronts and 275/35r rears (suggested by the retailer). Does anyone know what aspect ratio I can put on 20"s without affecting my current ride comfort and performance?

Here are the wheels I am deciding between:

Vossen CV1:

Vossen CV3:

Those are nice as well.

I too was looking at the Conti DWS tires, some of the guys on the F10 section either have had issues with or dont care for them.

If I go 20, I'm looking at the Michelin PS A/S plus tires. They are about $300 more for a set of 4.

@jadnashuanh:
you, sir, are very knowledgeable and this is exactly the wisdom I was searching for. Many good points mentioned in your post and I appreciate that since I did not even think about those in the first place. Exactly why I frequent this board.

if i did the math for the retailer's suggested tire configuration on the same 20" wheels:

front: 245/35 = (245/25.4)*.35*2 = 6.75 + 20 = 26.75, or 3.25% deviation from rolling diameter
rear: 275/35 = (275/25.4)*.35*2 = 7.57 + 20 = 27.57, or 0.29% deviation from rolling diameter

the rears seem to be closer to rolling dia. but front's are way off. I think 245/40's would get it closer but would then be above the stock rolling dia. Is this an issue?

Do you think a 2.9" (front) or 2.1" (rear) variance from the stock tire's would have *significant* risk for comfort? tire damage? Should I opt for 19's?

Thanks again for all the info. Any more you can add to the above, well, just makes you absolutely awesome.

Differences in rolling diameters become more of an issue with x-drive than rear-wheel drive as the bigger the difference front/rear, the more likely the computer is to think that there's slippage and try to do something about it.

There is a potential handling advantage of shorter sidewalls since from the same tire but different sizes, a lower aspect ratio should have less 'squirm' and flex. But, it's the flex that affects comfort, squirm isn't great on any tire as it adds heat and wear. But internally, I'd guess (don't know) that they modify the belt wraps and tread pattern a bit to compensate.

The shorter the sidewall, the more likely any impact will damage either the tire or the wheel, and will affect the comfort. The tire is a balloon...it will only deflect so much before you damage the cords or impact the wheel. As you try to compress a tire, the tire pressure increases as the volume decreases, sort of like an air spring. The more air you start with, the bigger range you have. You still need to hold the car up, so you'll notice that the lower aspect ratio tires generally require higher pressures, making them stiffer, and thus also affecting the ride. Higher pressures and shorter sidewalls, stiffer ride.

JAD, Nice job with your explanations.

Originally Posted by wchewbaka

JAD, Nice job with your explanations.

Agreed!

Originally Posted by starryeyed

Agreed!

+1000,

His responses and detail for each reminds me of my delivery at the welt where they had an answer for anything related to the car. Cleared up a lot of ???'s for me. Thanks again!

Originally Posted by mycabrandz

+1000,

His responses and detail for each reminds me of my delivery at the welt where they had an answer for anything related to the car. Cleared up a lot of ???'s for me. Thanks again!

+1001.

I'm about 1-2 months from pulling the trigger on the 312s.

Originally Posted by mycabrandz

Hey Bryan, I'm also looking into bumping up from 18's to 20's and am wondering what that does to ride comfort and performance.

My 535GT has 18x8.0 with 245/50 size tires all around and they look too blah for me but I like the ride comfort. I tried to upgrade as part of the order but could not since it was an ED. I am looking at ordering a staggered 20" configuration with Conti DWS 245/35r fronts and 275/35r rears (suggested by the retailer). Does anyone know what aspect ratio I can put on 20"s without affecting my current ride comfort and performance?

Here are the wheels I am deciding between:

Vossen CV1:


Vossen CV3:

Good luck with your choice and thanks for thinking of Vossen.

Originally Posted by jadnashuanh

Differences in rolling diameters become more of an issue with x-drive than rear-wheel drive as the bigger the difference front/rear, the more likely the computer is to think that there's slippage and try to do something about it.

There is a potential handling advantage of shorter sidewalls since from the same tire but different sizes, a lower aspect ratio should have less 'squirm' and flex. But, it's the flex that affects comfort, squirm isn't great on any tire as it adds heat and wear. But internally, I'd guess (don't know) that they modify the belt wraps and tread pattern a bit to compensate.

The shorter the sidewall, the more likely any impact will damage either the tire or the wheel, and will affect the comfort. The tire is a balloon...it will only deflect so much before you damage the cords or impact the wheel. As you try to compress a tire, the tire pressure increases as the volume decreases, sort of like an air spring. The more air you start with, the bigger range you have. You still need to hold the car up, so you'll notice that the lower aspect ratio tires generally require higher pressures, making them stiffer, and thus also affecting the ride. Higher pressures and shorter sidewalls, stiffer ride.