[duglas]

Hi i am planning to mount 245 45 19 front and 275 40 19 on rear on my
F10 520 sedan.I will do it because i want a smoother ride and also to
fill up the wheel arch better without lowering the car.
Has anyone in here done the same or have a picture how it looks?

[Grover432]

Originally Posted by duglas

Hi i am planning to mount 245 45 19 front and 275 40 19 on rear on my
F10 520 sedan.I will do it because i want a smoother ride and also to
fill up the wheel arch better without lowering the car.
Has anyone in here done the same or have a picture how it looks?

I'm curious, does increasing the wheel size fill in the wheel well? I thought that with the increased wheel size came a corresponding reduction in the height of the sidewall to maintain the same overall circumference of the wheel/tire package. To try and confirm this I checked with a tire size calculator I found online:

528i: 225/55 R17 OD = 84"
528 X Drive: 245/45 R18 OD = 83.8"
535 X Drive 245/40 R19 OD = 83.9"
550X Drive: 245/40 R19
M5: 265/35 R20 OD = 85.7" (front)
295/30 R20 OD = 84.7" (rear)

Based on the above, it looks like you'd need to go to a 20" wheel to appreciably "fill" the wheel well. The M5 fronts are 1.7" larger (OD) than a base car, so .85" would be filled in the wheel well. The rears would add .7" to the OD of a base car and .35" would be added to "fill" the wheel well.

It seems to me that if you want to fill the wheel well, you need to lower the suspension. Maybe the wheel well fill is an optical illusion with the larger wheel material?

As to the ride, I agree that with a properly tuned suspension a larger wheel seems to give a smoother ride. I wonder about the shorter sidewall on a car that doesn't have a matched set of springs bringing a harsher ride?

Non conclusions on all of this, just musing.

[AVIMAX]

245-40-19 calculates to an OD of 26.7". 245-45-19 calculates to an OD of 27.7", an increase of 1.0" in diameter. So in theory it should close the gap by 0.5" but also raise the ride height by 0.5". Might just do the trick for what you are looking for.

I always wonder how sensitive the car's electronics are to changes in wheel/tire diameter. With all the DTC, DSC, ABS etc, are the cars electronics setup to work best with the stock wheel/tire diameters, or is it only a problem if the front and rear wheel/tire diameters are mismatched? I don't know the answer to this, but I am curious. Is it like the flat tire monitor that doesn't care what the diameter is but must be reset when any changes are made to calibrate the system with a baseline?

I too would like to see photos of this setup.

[Grover432]

Originally Posted by AVIMAX

245-40-19 calculates to an OD of 26.7". 245-45-19 calculates to an OD of 27.7", an increase of 1.0" in diameter. So in theory it should close the gap by 0.5" but also raise the ride height by 0.5". Might just do the trick for what you are looking for.

I always wonder how sensitive the car's electronics are to changes in wheel/tire diameter. With all the DTC, DSC, ABS etc, are the cars electronics setup to work best with the stock wheel/tire diameters, or is it only a problem if the front and rear wheel/tire diameters are mismatched? I don't know the answer to this, but I am curious. Is it like the flat tire monitor that doesn't care what the diameter is but must be reset when any changes are made to calibrate the system with a baseline?

I too would like to see photos of this setup.

That is a good question because the suggestion to change to a taller sidewall with the same wheel size will definitely have some affect. As noted from my calculations above, BMW keeps the circumference of the tire ( and by that the diameter of the wheel/tire combination) the same for all car versions, regardless of wheel size (except M5). I think there must be a reason for it. A larger diameter will upset the speedometer and I wonder if the different rotational speeds will upset other electronics (stability, etc.).

[AVIMAX]

I think this is what you are looking for. Looks good to me.

http://f10.5post.com/forums/showthread.php?p=11807624

[RMcoolX]

OP, I have the same tire sizes that you have elected to go with. I too wanted to go with 19s instead of 20s because I wanted to try and keep the 'silky smooth' ride as near to stock as possible. I researched 19s vs 20, as well as tire choices that sacrificed sport handling in favor of maximizing comfort. The setup I have did not disappoint, and I am a happy as I can be with the outcome.

[Bobby_Drake]

Originally Posted by RMcoolX

OP, I have the same tire sizes that you have elected to go with. I too wanted to go with 19s instead of 20s because I wanted to try and keep the 'silky smooth' ride as near to stock as possible. I researched 19s vs 20, as well as tire choices that sacrificed sport handling in favor of maximizing comfort. The setup I have did not disappoint, and I am a happy as I can be with the outcome.

How's the ride comfort and handling compared to stock 18s? Do you notice any difference in the suspension or speedometer readings?

[duglas]

Thanks for the info guys.
Im a little worried about the auto transmission and if the abs wil work.
RMcoolIX:Your car looks avesome what wheels do you have?
also are you sure it the tires are 245 45 19 275 40 19 on the pictures? because in the link that AVIMAX shared the tires look much bigger than on your car.

[awins1]

I am also considering going with 245/45/19 on my 550xi. I have gone through 5 replacement GY run flats now in 12k miles. Going with 45s seems like would be a better choice with 19in wheels as a taller sidewall would offer more protection to the wheels here in NY area. I'm also interested in hearing more opinions/comments about potential issues, if any, going with such tire size.

[cdmulders]

I am running 245/50/18s (square setup) for my winter tires/wheels. This is one profile size above what BMW installs on 18" OEM wheels, which I believe is 245/45/18. No issues whatsoever. My speedo reads about 5kph (3mph) slower at highway speed than when I run my 245/40/19 summer wheels/tires.

I do not think running 245/45/19 is going to pose a problem.

[RMcoolX]

Originally Posted by duglas

RMcoolIX:Your car looks avesome what wheels do you have?
also are you sure it the tires are 245 45 19 275 40 19 on the pictures? because in the link that AVIMAX shared the tires look much bigger than on your car.

I just double checked my invoice to make sure I'm telling you correctly. My fronts are 245/40/19, and the rears are 275/35/19. Sorry for any confusion. Thanks for the compliment.

Originally Posted by Bobby_Drake

How's the ride comfort and handling compared to stock 18s? Do you notice any difference in the suspension or speedometer readings?

Ride comfort is not quite as plush as the stock 17s that my base car came with, but it's pretty dang close. Although tests at Tire Rack resulted in the Bridgestone Potenza RE760 Sport being the best tires in its test pool for comfort, I fully expected to lose some level of comfort. It did, but not near to the point that I regret the move. Handling improved a little, but not enough to change the overall feel of the car. I notice no difference in the suspension either, and the speedo reads the same being that I selected +2 sizing that kept the overall tire diameter near the same.

[M5Beast_NYC]

Im interested in going 45 series tires as well as I had two bubbles in less than a month. Ny roads really sucks. With a 1" difference, does this mean you miles are increasing more rapidly than oem?

[RMcoolX]

Originally Posted by Carbonm3ny

Im interested in going 45 series tires as well as I had two bubbles in less than a month. Ny roads really sucks. With a 1" difference, does this mean you miles are increasing more rapidly than oem?

It means your miles will increase less.

[rkstar9]

Originally Posted by RMcoolX

I just double checked my invoice to make sure I'm telling you correctly. My fronts are 245/40/19, and the rears are 275/35/19. Sorry for any confusion. Thanks for the compliment.



Ride comfort is not quite as plush as the stock 17s that my base car came with, but it's pretty dang close. Although tests at Tire Rack resulted in the Bridgestone Potenza RE760 Sport being the best tires in its test pool for comfort, I fully expected to lose some level of comfort. It did, but not near to the point that I regret the move. Handling improved a little, but not enough to change the overall feel of the car. I notice no difference in the suspension either, and the speedo reads the same being that I selected +2 sizing that kept the overall tire diameter near the same.

I thought different diameter tires are not good for x drive?

[Qsilver7]

Originally Posted by rkstar9

I thought different diameter tires are not good for x drive?

See last box in pic below in regards to AWD and different sized tires (mixed aka "staggered"):