[felixlamb]

Hey,

I’m looking to purchase a set of all-season tyres for our UK winter. The alloys are on their way already.

I’m going for a 245/35/19 square set up, so I can rotate the tyres as necessary in the future.

However, the majority of good tyres in this size only have a load rating of 93 (650kg), whereas the OEM ZTK rears have a rating of 96 (710kg).
650kg per tyre is 1300kg per axle still, and 2600kg total, which seems plenty sufficient?

Now, given it’s winter, I’m hardly going to be hooning it around the place, so… will a 93 load rating be okay?

My gut is yes, as some of the allowed tyre options are 225/40/19 93Y (same load rating) and 225/30/20 92Y (lower load rating), but they are different sizes and profiles.

Source: https://g20.bimmerpost.com/forums/sh...34&postcount=2

[Pentland]

Winter Continental Winter Contact TS860 SSR are the BMW recommended and star marked winter tyres. Fronts are 93H and rear 96H. Staggered set up.


EDIT:
My sizes on zkt - BMW approved.
225/40 19 93H and 255/35 19 96H

[ILikeBimmers]

Online I'm finding that the minimum load index is 92 https://tirepressure.org/bmw/m240i-xdrive/2022#Coupe. The bigger concern I'd warn about is that generally it's encouraged to minus size tires as the larger contact patch is more vulnerable to snow float. I believe square setups are also better for winter stability and also tire rotation.

Here is a comparison with the 19" rims you are going to choose with what I have for my winter setup which is an 18" Michelin X-Ice Snow tire for visual comparison: https://www.calculator.net/tire-size...culate#compare.

I also have the ZTK (High Performance Tire and Cooling Package) and 18" rims, as far as OEM goes, will clear the larger brakes that the ZTK variants come with. If you're going with a second set of rims, you can double check with the people who will balance the tires on the rims for clearance, as I'm assuming you don't have that equipment at home since you're asking about tires here.

[felixlamb]

It’s a toss up between 225/40/19 or 245/35/19 then I think…

[DAXXR]

All uk m240i are xdrive, so your car will not be happy with different sized tyres than standard.
Just get the correct sized fronts and rears.

[Pentland]

Note that, as is the case with the winter tyres I suggested, BMW advise a speed restriction on the vehicle of 130mph. They even offer a specific sticker for you to attach to the dash to indicate the fitment of winter tyres and the associated speed reduction. I think it’s law to do this in Germany.

That would then raise the question, should your speed be similarly limited if using cross climates?
I’m not suggesting that anyone in the UK would be driving at 130mph let alone maxing out at 155mph on public roads but you should be aware of any limitations with tyre choice.

[felixlamb]

Originally Posted by DAXXR

All uk m240i are xdrive, so your car will not be happy with different sized tyres than standard.
Just get the correct sized fronts and rears.

245/35 / 255/35 (ZTK) is a 1.07% difference.
225/40 / 255/35 (non-ZTK) is a -0.23% difference.
245/35 / 245/35 is a 0% difference.

Explain why the car won’t be happy? That’s well within the tolerance permitted by the existing OEM options available.

[Pentland]

Originally Posted by felixlamb

245/35 / 255/35 (ZTK) is a 1.07% difference.
225/40 / 255/35 (non-ZTK) is a -0.23% difference.
245/35 / 245/35 is a 0% difference.

Explain why the car won’t be happy? That’s well within the tolerance permitted by the existing OEM options available.

The tolerance is cross axle not front to back. You’ll be fine.

[Jayphil]

Originally Posted by felixlamb

245/35 / 255/35 (ZTK) is a 1.07% difference.
225/40 / 255/35 (non-ZTK) is a -0.23% difference.
245/35 / 245/35 is a 0% difference.

Explain why the car won’t be happy? That’s well within the tolerance permitted by the existing OEM options available.

ZTK difference is actually 0.8% so under 1% which is the acceptable limit variance agreed by most.

Originally Posted by Pentland

The tolerance is cross axle not front to back. You’ll be fine.

The tolerance (of 1%) for xdrive most talk about is front and rear. Obviously cross axle it should be the exact same size.

[Pentland]

Originally Posted by Jayphil

The tolerance (of 1%) for xdrive most talk about is front and rear. Obviously cross axle it should be the exact same size.

Can you show me the BMW document that stipulates that?
I believe the 1% tolerance across all tyres is regurgitated internet myth.

I can believe a tolerance of say 2mm cross axle and 3mm front to back but call bull on 1% across the board. Nobody is buying 4 new tyres if they have a puncture after 10k miles.

[DAXXR]

Explain why the car won’t be happy

Traction control will kick in exiting roundabouts.
Been in a m240i when it happened, so just be aware you can have issues with different sized tyres than standard

[Jayphil]

Originally Posted by Pentland

Can you show me the BMW document that stipulates that?
I believe the 1% tolerance across all tyres is regurgitated internet myth.

I can believe a tolerance of say 2mm cross axle and 3mm front to back but call bull on 1% across the board. Nobody is buying 4 new tyres if they have a puncture after 10k miles.

You sound a bit rude, I was just trying to help…

I did not say that I had a document from BMW, I said 1% agreed by most or that people talks about. BMW specify some tire sizes for xdrive (summer, winter setup etc) and star rated tires all of which are always within 1% difference … but some rear wheel drive model have greater differences… if this is not enough for you it is enough for me to stay on the safe side.

Also when you have a tire problem is is always recommended to change the two tires of the front or rear especially if they were significantly worn out. Not every body does it but it does not mean it is not the best thing to do but obviously not the best for the wallet that is for sure.

[felixlamb]

Originally Posted by Jayphil

ZTK difference is actually 0.8% so under 1% which is the acceptable limit variance agreed by most.

The tolerance (of 1%) for xdrive most talk about is front and rear. Obviously cross axle it should be the exact same size.

245/35/19 circumference is 654.1mm
255/35/19 circumference is 661.1mm

661.1mm is 1.07% greater than 654.1mm... isn't it?

[Pentland]

Originally Posted by Jayphil

You sound a bit rude, I was just trying to help…

I did not say that I had a document from BMW, I said 1% agreed by most or that people talks about. BMW specify some tire sizes for xdrive (summer, winter setup etc) and star rated tires all of which are always within 1% difference … but some rear wheel drive model have greater differences… if this is not enough for you it is enough for me to stay on the safe side.

Also when you have a tire problem is is always recommended to change the two tires of the front or rear especially if they were significantly worn out. Not every body does it but it does not mean it is not the best thing to do but obviously not the best for the wallet that is for sure.

As I said, the problem with the “help” you provided is it’s unsubstantiated which is why I asked for some evidence. I’m not criticising you personally, just this “1 % BMW tolerance” figure keeps getting spouted out and repeated without question and becomes the norm.

Agree it’s correct to replace two front or rear tyres if the new diameter is reasonably different to the existing an the same axel but it’s simply not true to also replace the other axel’s tyres as well which is what you are implying with this tolerance on xdrive.

[IanH]

Agree that the 1% difference is a rumor and you do not need to stay with oem tire sizes only lol.

Try to keep them similar diameter. Many brands will actually tell you to replace all tires when you destroy one, it's an industry wide CYA so they can deny warranty work.

[Jayphil]

Originally Posted by felixlamb

245/35/19 circumference is 654.1mm
255/35/19 circumference is 661.1mm

661.1mm is 1.07% greater than 654.1mm... isn't it?

Sorry this calculator gave me the .8% figure showing 655 vs 660 for some raison…
https://tiresize.com/comparison/