[b58.oscar]

I want new tires for my x drive m340 would 255/35/19 fronts and 285/35/19 rears fall under the 1% rule? i’m not sure how to calculate it.

[zlatko]

Are you kidding?! - that is roughly 10% difference! You must use smaller sidewall profile fro the rears, e.g. 30.

PS. It is easy to calculate: the second number gives you the sidewall height like percentage from the tyre width. In your case 255*0.35=89.25mm, 285*0.35=99.75mm. That is a 1cm difference(out of ~10cm sidewall)

[ultrared93]

Originally Posted by b58.oscar

I want new tires for my x drive m340 would 255/35/19 fronts and 285/35/19 rears fall under the 1% rule? i’m not sure how to calculate it.

Michelin's website (https://www.michelinman.com/) has a wealth of information regarding sizing. I would compare the number of revs/mile. For example, the 255/35x19 PS A/S4 shows 799 revs/mi. Compare that with the value for the other size to see if they are within 1% of each other. Now keep in mind that tires from other manufacturers may vary slightly, but this should get you close.
One other consideration is rim width. Michelin also lists acceptable widths for each size. I think you will need wider than stock rims to mount the sizes you are considering.

[TurtleBoy]

Those have a bigger difference in circumference than they should. Here is a site that will do the math for you.

https://tiresize.com/comparison/

[b58.oscar]

thank you

[Matic94]

If you want to stick with those fronts, change the rears to 295/30/19 and it will be just about perfect.

[b58.oscar]

I think i’m going to go with 245/40/19 in the front and keep 285/35/19 in the rears.

[zlatko]

Originally Posted by b58.oscar

I think i’m going to go with 245/40/19 in the front and keep 285/35/19 in the rears.

That will work as far as the transfer case is concerned. Don't know how it will affect the handling, but you can report back after the change

[G30M]

Originally Posted by b58.oscar

I want new tires for my x drive m340 would 255/35/19 fronts and 285/35/19 rears fall under the 1% rule? i’m not sure how to calculate it.

you know that wider wheels, bigger tires are heavier and so your car will accelerate slower ... just so you know.

[Retrofyt]

I just put a pair of Apex’s on my 2021 m340i xDrive. Running 255s in front and 265s in rear. I’d say fitment is perfect and handling is pretty much the same - definitely can feel the added surface area when turning the wheel and xDrive trying to compensate. No rubbing either. Not sure what 1% rule is but spent lost of time on wheel-size.com in order to make sure everything was perfect.