[AgentSmith666]

I run the standard 245/35 and 275/30 on my 20in wheels on the M550 LCI. I got a decent offer on a set of 20 inch 668m wheels with winter tires, but for some reason the owner has chosen to run 245/40/20 and 275/35/20

Does anyone run this setup? The gain in circumference is 1-1.25 inch. Would there be any problems?

[AP]

The issue that comes to mind is regarding the speedometer
My physics isn’t up to the grade to say whether that means your speed will under or over read in comparison to the existing tyres
(Does entering in custom tyre settings in the idrive affect that ??)

[AgentSmith666]

Originally Posted by AP

The issue that comes to mind is regarding the speedometer
My physics isn’t up to the grade to say whether that means your speed will under or over read in comparison to the existing tyres
(Does entering in custom tyre settings in the idrive affect that ??)

The 245/40 setup will under read the speed, showing 57 mph instead of 60 mph according to an online calculator.

But I am more concerned about the tires rubbing into something. There seems to be about 1.4 inches of a space between the current tires 245/35 and the fender (not sure if the suspension is closer or not, hard to gauge), and this new setup will eat 0.5-0.6 inches of that space.

[BNV Peter]

The 245-40-20 F 275-35-20 R
This is the tire size that I am going with next summer for my new tires setup.
Looks much better on the Car, and I prefer the extra load capacity of the tires.
This will Help big time with dealing with Potholes in the city of Toronto.
Thank you 🙏

[tjbuggy2b]

With stock size wheels, such as 668m, and stock ride height, I'd bet they should be fine. They're less than 1" larger in diameter, which is only about a half inch closer to the fenders, etc. People lower they're cars much more than that difference all the time, with more aggressive wheel offsets.

[Ptree1822]

i am no issues

[w1zk1d]

Same here, no issues, and I like it. I am running 245/40/20 and 275/35/20 on my winter setup. I might do 255/35/20 and 285/30/20 for the summers which would also increase the sidewall slightly.

[Jodway]

I ran 245/40 and 275/35 on my stock 20's for almost 2 years. Car is lowered on Dinan springs and had 17.5/20mm spacers as well. My speedometer was actually MORE accurate according to GPS comparison with this setup than it is with my current 255/40 and 285/35 setup on 19's

[MRDILLONS]

I made switch a couple of months ago and really loving my car now, luxury ride.

[ezaircon4jc]

On the question of size...

Will a 285 tire fit on the (20"X9") 759i wheel? I noticed that a 285/30 is closer in revs per mile (within 2) than a 275/30. It also affords a little more sidewall than the 275. If the tire will fit, I plan on going with the 285. I have looked at tire calculators and other forums. The forums (not necessarily BMW) seem to indicate it will fit.

What say the braintrust?

[G30M]

Originally Posted by AP

The issue that comes to mind is regarding the speedometer
My physics isn’t up to the grade to say whether that means your speed will under or over read in comparison to the existing tyres
(Does entering in custom tyre settings in the idrive affect that ??)

interestingly (using a dedicated GPS speed tool) i discovered my M340i corrects itself when i changed tire sizes!

(went to different tire size and speedo was way off at first ride. 2 hrs later rechecked with GPS tool, back to the standard 3.5kph difference it was prior)

well i changed back to the previous tires today so will retest. hopefully will self correct again.

[The_Hall_Way]

I too am interested in tire fitment, I'm going to ditch the RFTs for some proper tires & was thinking of keeping the 245/35 front but running a 285/35 rear on a stock setup w/668s on MY20 M550. Curious if anyone can confirm fitment will be ok?

I appreciate any help, I've searched so many times & cannot find a clear answer.

[G30M]

Originally Posted by The_Hall_Way

I too am interested in tire fitment, I'm going to ditch the RFTs for some proper tires & was thinking of keeping the 245/35 front but running a 285/35 rear on a stock setup w/668s on MY20 M550. Curious if anyone can confirm fitment will be ok?

I appreciate any help, I've searched so many times & cannot find a clear answer.

drivetrain will explode

[The_Hall_Way]

Originally Posted by g21

drivetrain will explode

Thanks mate

[RL_M550i]

Originally Posted by MRDILLONS

I made switch a couple of months ago and really loving my car now, luxury ride.

Are those tires 245/40 and 275/35 ?

[MRDILLONS]

Originally Posted by RL_M550i

Are those tires 245/40 and 275/35 ?

Yes they are and the fit fine nor will it void your warranty.

[cna90]

I switched to 245/40R20 and 275/35R20 on 648M rims from a 7 series last year. No need for spacers anymore with these rims. Never had issue. In iDrive, I set it to R19 as it’s the same ratio plus air pressure is correct with the R19 in iDrive. Drive is more comfortable but the steering in more numb than it was before since they made these cars with hard runflats tires. The feeling gets lost with none runflats.
Speedo seems to be exact vs before that was always showing higher than it actually was!