[donny95]

So I just got a new set of wheels and need help figuring out the best meaty tire setup as I see too many different answers and I think it would help if I give the exact specs of the new wheels along with the tires I plan to get to get some good advice from fellow forum members

Car is 340 xdrive
Car is not lowered nor will be

Wheel specs:
front 19x8.5 +35 72.6
rear 19x9.5 +35 72.6

Planning to get Firestone Firehawk Indy 500

Possible setup I've been looking at is 235 265

I've heard 245 265, 245 275, 255 275, 235 275
All sidewalls being 40 from and 35 rear or 35 front 30 rear

I've seen complaints that the 30 sidewall is too thin and can be prone to popping or/and causing damage to the rim if that does end up happening. Streets in Toronto in some areas can be full of potholes.

Sorry I am still new to all these tire spec terms and just want a nice meaty setup that doesn't hinder performance compared to the stock 225 255 19 setup these cars come with so please if anyone can help thank you!!

[captainfast]

Looking at 235/40 and 265/35 is good for xDrive setup as commented by most users here. Main thing to note is that odometer speed/mileage reading < actual speed/mileage in this setup but not by much IMO.

[J555]

You have basically two options:

1. 235/40+265/35:
+ slightly sharper handling and braking
+ less rolling resistance
+ no potential rubbing issues
+ rims appears a bit bigger (due to shorter sidewall)
+/- less impact on speedo readout
- not as meaty as it can be
- less total grip

2. 245/40 + 275/35:
+ slightly more comfortable
+ slightly better protection for the rims
+ better steering feel
+ more front grip
+ beautiful meety rear fitment
+/- true-to-life speedo readout
+/- slightly more lifted car (due to bigger overall diameter)
- depends on tires, slight rubbing may occur in front (you won't notice)
- I suspect that depends on tires, slight rubbing may occur with high load also in rear (you can possibly confirm it with somebody running such setup)
- slightly less turn-in sharpness

All things considered, unless you want the meatiest setup, I would consider the first option as the best compromise. Have no experience with the Firestone tires, thus cannot comment the fitment.

[Insane435]

Any reason 255/35/19 265/35/19 wouldnt work? they are 1.2% different in size.

[Th3Walrus]

Sure, if you want to blow your transfer case.

[Insane435]

Originally Posted by Th3Walrus

Sure, if you want to blow your transfer case.

What are specs required to keep within the safe parameters of the transfer case? Isn't it 1%? So you're saying the extra 0.2% will destroy the car?

[Th3Walrus]

I personally know someone who's been through 4 transfer cases (under warranty) between two 550i, running the recommended/available optioned 20" tire sizes which were exactly 1% different front/back. 245/35R20 and 275/30R20.

Update: It was actually 4 transfer cases on his first 550i. BMW then took it back and he got another one, with the same tire sizes, and hasn't had a problem.

[Insane435]

Originally Posted by Th3Walrus

I personally know someone who's been through 4 transfer cases (under warranty) between two 550i, running the recommended/available optioned 20" tire sizes which were exactly 1% different front/back. 245/35R20 and 275/30R20.

I assume that is a different part than the f30. I'd like to know if 1.2% is acceptable because getting that 255 up front would do wonders. Someone has to have tried a setup near that difference.

[donny95]

Originally Posted by J555

You have basically two options:

1. 235/40+265/35:
+ slightly sharper handling and braking
+ less rolling resistance
+ no potential rubbing issues
+ rims appears a bit bigger (due to shorter sidewall)
+/- less impact on speedo readout
- not as meaty as it can be
- less total grip

2. 245/40 + 275/35:
+ slightly more comfortable
+ slightly better protection for the rims
+ better steering feel
+ more front grip
+ beautiful meety rear fitment
+/- true-to-life speedo readout
+/- slightly more lifted car (due to bigger overall diameter)
- depends on tires, slight rubbing may occur in front (you won't notice)
- I suspect that depends on tires, slight rubbing may occur with high load also in rear (you can possibly confirm it with somebody running such setup)
- slightly less turn-in sharpness

All things considered, unless you want the meatiest setup, I would consider the first option as the best compromise. Have no experience with the Firestone tires, thus cannot comment the fitment.

Thank you for this one, this is the dilemma I am in, it's very hard finding someone with this setup that can comment on this probably bc they are not on the forums to be able to answer lol. In your opinion would the first option affect acceleration at all or would it be so small that it wouldn't be noticeable.

[J555]

Originally Posted by Insane435

What are specs required to keep within the safe parameters of the transfer case? Isn't it 1%? So you're saying the extra 0.2% will destroy the car?

Nobody knows, the best practice says to keep the diameters as close as possible. If different, the rears should be smaller. However, there are numerous exceptions even from these basic rules, as setups with differences bigger than 2% with no issue, or even some Alpina factory setups reaching 2% (with rear bigger diameter). On the other hand, some others reported transfer case jerkiness already around 1.5%.

Originally Posted by Th3Walrus

I personally know someone who's been through 4 transfer cases (under warranty) between two 550i, running the recommended/available optioned 20" tire sizes which were exactly 1% different front/back. 245/35R20 and 275/30R20.

I am not aware of anybody, who knows the reason - the transfer cases can die for several reasons. I personally know x-drive cars of exactly the same tire setup with absolutely no issues within 150-200,000 miles. I personally know a car with a broken transfer case, and the root cause was a bad drive shaft. Have one set of wheels with these tire sizes and I like it a lot, no issues. Would be interesting to hear, if he spotted some issues with the transfer case prior to it got broken (which should be the case of different diameters and struggling transfer case). Can you share the details, please?

Originally Posted by Insane435

I assume that is a different part than the f30. I'd like to know if 1.2% is acceptable because getting that 255 up front would do wonders. Someone has to have tried a setup near that difference.

I've seen few people fitted M3/M4 wheels with 255/275 on x-drive. You can fit 255/35/19 + 295/30/19, albeit it is more or less the widest tires possible without heavy modifications. To my taste, they are too wide, causing extreme rolling resistance, and increasing the risk of aquaplaning (and do not address the original request for meaty tires and filling the fender gaps). I expect 255 squared to be a great setup for x-drive, but have no personal experience.

Originally Posted by donny95

Thank you for this one, this is the dilemma I am in, it's very hard finding someone with this setup that can comment on this probably bc they are not on the forums to be able to answer lol. In your opinion would the first option affect acceleration at all or would it be so small that it wouldn't be noticeable.

Well, the 235/40 + 265/35 is a very popular staggered fitment, even with similar offsets you have, see example: https://f30.bimmerpost.com/forums/sh...71&postcount=6

While measurements can show some, I would be surprised if you will feel any negative difference in acceleration. Depends on your current setup, the car can accelerate faster off the line with wider and better tires; especially with a tuned engine (due to less/no slip).

[Th3Walrus]

Update, I checked with him and it was actually 4 transfer cases on his first 550i. BMW then took it back and he got a different one, with the same tire sizes, and hasn't had a problem.

[Silverlining_m2]

I run 235/35 amd 265/30 on my LOWERED 435i. If I didn't lower it I would run 235/40 and 265/35. I believe those sizes would still work for x drive as well.

[J555]

Originally Posted by Th3Walrus

Update, I checked with him and it was actually 4 transfer cases on his first 550i. BMW then took it back and he got a different one, with the same tire sizes, and hasn't had a problem.

Many thanks for clearing that up!

[anujatd]

is it safe to run 225/45/19 front and 255/40/19 rear on xdrive? wheel specs are 19x8.5 et 30

Thanks!

[J555]

Originally Posted by anujatd

is it safe to run 225/45/19 front and 255/40/19 rear on xdrive? wheel specs are 19x8.5 et 30

Thanks!

No, as the tires are 27" in diameter and will rub. Max diameter without rubbing is 26.7-26.8". If all your wheels are of the same spec, you can go 235/40 or 245/40 square.

[anujatd]

Thanks- do you know if the max diameter is the same for a 440i xdrive gran coupe as well?

[J555]

Originally Posted by anujatd

Thanks- do you know if the max diameter is the same for a 440i xdrive gran coupe as well?

If I am not mistaken, the wheel wells of 3-er and 4-er are a bit different in width and shape, but that doesn't affect max diameter with these tire sizes.

[weehe126]

Pretty sure the gran coupe came stock with one profile larger tires, 27"

[alohasurftoad]

Originally Posted by weehe126

Pretty sure the gran coupe came stock with one profile larger tires, 27"

Of the F3/4 series, only F34 3-series gran turismo came with 27".

I have a f36 gran coupe

[J555]

Originally Posted by weehe126

Pretty sure the gran coupe came stock with one profile larger tires, 27"

Not really, only GT (F34) uses larger diameter.