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BMW 5-Series (G30) Forum Wheels | Tires | Suspension | Brakes | Chassis Wheel + tire setup G30 540iX - options

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      02-05-2020, 05:55 AM   #1
luke1990
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Wheel + tire setup G30 540iX - options

Hi guys,

Got my G30 540i, aligned on tuning and now its onto wheels and tires. Car came with 18" so I keep those for winter - looks good enough for me (I have bluestone mettalic with black OEM 18s).

Ill preface this by my objective and context:
-> I don't want to compromise ride quality noticeably -> I came from F36 435d which was harsh on 19s even with Adaptive M suspension
-> Tied to that, Im from Eastern Europe so roads are not good; my 19s had to get fixed up after less than a year of driving (and they were OZ Leggera's - so while not forged not a bad quality)
-> Car has Adaptive drive (DDC + ARS)
-> I don't plan to lower the car
-> I like spirited driving on backroads - so wheels should match that; might even take it to track one of these days + the car will be pushing 540-600WHP
-> I ideally don't want to have issues with insurance/ technical check
-> The car is xDrive - so I think similar tire diameter front/rear is important

With that in mind - and please comment to any point here or overall:
1. I'm leaning towards 19s over 20s - for comfort and sporty driving; I still think they look ok

I have a big dilemma on wheel + tire setup. What I am thinking is 255/40/19 + 295/35/19 with 19/9 ET 23 front 19/10,5 ET37 rear; I think I read on 20s with 255/295 there was no rubbing
2. 255 + 295 should be a good combo right? Here it looks like the diameter is the same and is a better fit than 265/295 where the fronts are larger and difference is bigger. Here is comparison of front and back
3. Anybody knows why BMW is putting 245/40/19 and 275/40/19 though where the front tire is larger? As opposed to having 255 and 275?
4. Also - anybody knows what kind of speedo error will I get from going to 245/275 to 255/295?
5. KEY: Would anybody recommend going to non staggered setup more akin to M5? E.g. 275/40/19 on 19/9,5 ET26 with 285/40/19 on 19/10,5 ET28
6. KEY: Last - the M5 is running larger diameter tires (i.e. 285/40 vs 275/35). I've read that people did run a size bigger without rubbing issues, but - probably not with wider than stock tires? Does the M5 have different wheel arches?

THANKS A TON GUYS!
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      02-05-2020, 10:08 AM   #2
Superjackson
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Larger diameter tires make your acceleration less explosive but M5 has shorter gearing to make up for it.
Your 255/295 setup will fit easily.
Xdrive is decently tolerant and 265/295 won't have any problems since the difference is only 1%ish.
The Dinan m550i used 265/295 on 20x9ET28 + 20x10ET40.
Staggered vs square tire setup is based on your preference. Squared is more fun but less stable for handling.
The maximum I've tested to work in the front is 275 on 20x9.5ET28, actually just the stock M5 front setup lol. The rear can fit up to maybe 325, 315 for sure on a 11" wheel with ET 45.
M5 front fender is 15mm wider than our cars, their rear fenders are exactly the same but their hubs are more pushed in, making the M5 require more aggressive offsets for the rear.
There's not much information online about wheels for these cars so I got all this knowledge from testing a lot of different wheels and spacers. Hope you will use this info well!
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      02-06-2020, 11:11 AM   #3
luke1990
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Quote:
Originally Posted by Superjackson View Post
Larger diameter tires make your acceleration less explosive but M5 has shorter gearing to make up for it.
Your 255/295 setup will fit easily.
Xdrive is decently tolerant and 265/295 won't have any problems since the difference is only 1%ish.
The Dinan m550i used 265/295 on 20x9ET28 + 20x10ET40.
Staggered vs square tire setup is based on your preference. Squared is more fun but less stable for handling.
The maximum I've tested to work in the front is 275 on 20x9.5ET28, actually just the stock M5 front setup lol. The rear can fit up to maybe 325, 315 for sure on a 11" wheel with ET 45.
M5 front fender is 15mm wider than our cars, their rear fenders are exactly the same but their hubs are more pushed in, making the M5 require more aggressive offsets for the rear.
There's not much information online about wheels for these cars so I got all this knowledge from testing a lot of different wheels and spacers. Hope you will use this info well!
Thanks a ton for great answer! A quick follow-up if I may:
- Why would larger diameter tires make you accelerate slower? For one they should reduce slippage for higher powered cars - which is positive; so why?
- The last question was more towards having bigger tires on top - i.e. 40 vs 35 on e.g. comparable 275. Standard is 275/35/19 if I'm not mistaken rear. For added comfort I'd like 275/40/19 - which I think guys made work here fine. But I'm afraid that wont work for 295/40/19 tire :/ ? Plus the speedo error would be large - up to 5%
- and last the speedo thing -> if I have 1-2% off - means that if I'm going 100kph it may show 102 or 98 right?
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      02-06-2020, 08:30 PM   #4
Superjackson
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Wheel + tire setup G30 540iX - options

Assuming there is no slippage, larger diameter tires make your gear ratio taller which basically decreases your acceleration but gives you more top speed at each gear. It's a really small difference, just like the speedo difference. 2% taller tires will make your speedo show a 2% lower number than before. Speed error is nothing to worry about, it will be consistently off by the same percent.

As for the 295/40/19, I don't think there would be any problem fitting that but you'd have to worry about 255/45/19 hitting the front inner swivels from being too tall.
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      02-11-2020, 08:42 AM   #5
luke1990
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Last edited by luke1990; 02-13-2020 at 09:38 AM..
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      02-13-2020, 09:37 AM   #6
luke1990
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Hey guys,

I've decided to try out 20"s and get size that can fit both larger diameter tire if I want to go to 255/295 as well as standard 245/275 with larger diameter (+5mm) - if I find the ride too lets just say not comfy .

For this I am thinking 20/8,5 front and 20/10 back - same as 7 series 20's (plus to save some weight over 20/9+20/10,5). Just 2 questions so I can go make the purchase:

1. Could anybody please confirm that 20/8,5 fit both 245/255s and 20/10 fit both 275/295s? Bonus question () why do BMW non-M cars often have thinner rims compare to tire-width (e.g. stock 540ix 245/35/20 on 20/8 w. 275/30/20 on 20/9) but M cars have it other way (wider rims to tire width) -> e.g. F90 M5 275/35/20 on 20/9,5 and 285/35/20 on 20/10,5)

2. Could you recommend offset/ET please? Stock 7 series are ET25/ET41, but seen here people doing ET25/36. What is the one I should go for with this? Especially considering I will be running 255/295s

Thanks a ton!

Last edited by luke1990; 02-16-2020 at 07:01 AM..
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