[felixlamb]

Hey,

I used to own an E89 Z4. Summers were original rims with 235/35/19 8J front, 265/30/19 9J rear for summers. For winter, I swapped on a square 225/45/19 7.5J and sorted fitment with spacers.

I'm looking to get a decent winter set up for the upcoming UK winter months for my new M240i xDrive. Ideally, I'd prefer a square set up, so that I can rotate from front to rear as appropriate, and likely thinking 18" rims as the tyres will be a little cheaper and will have a bit more sidewall.

Theoretically, I could get a set of 4 front alloys, either model 770 (8J ET20, or 798M (8.5J ET30), and they'd fit about right, with some 245s all around.

Is this an insane thing to do? It doesn't need to look pretty - that's what my 893Ms are for. It just needs to be functional, without looking horriffic or mucking up handling etc. I'm hoping used OEM alloys would be the most price-effective method too.

[Appash29]

What part of England?, I live in the north east and have never fitted winters to my last 4 x drive cars (420D, 435D, M135i or M240i).

[felixlamb]

Originally Posted by Appash29

What part of England?, I live in the north east and have never fitted winters to my last 4 x drive cars (420D, 435D, M135i or M240i).

Birmingham-way, but I also live in the middle of nowhere, with roads which are never salted. I've found winters to be beneficial in the past.

[JoeyJoeJo]

Before I got offered a great deal on an OEM set from my local dealer, I was pretty set on Autec Bavaris (18 inch square setup) from Mr Winter Wheels. Was about £1300 all in (oem spec tyres, OEM TPMS and mounting) and they have all the relevant EU certifications so you're sure of a good (and safe) fit.

They look good to me too.

[felixlamb]

Originally Posted by JoeyJoeJo

Before I got offered a great deal on an OEM set from my local dealer, I was pretty set on Autec Bavaris (18 inch square setup) from Mr Winter Wheels. Was about £1300 all in (oem spec tyres, OEM TPMS and mounting) and they have all the relevant EU certifications so you're sure of a good (and safe) fit.

They look good to me too.

Thanks - that's useful. Most 18" alloys should fit over the ZTK callipers right?

[JoeyJoeJo]

Originally Posted by felixlamb

Thanks - that's useful. Most 18" alloys should fit over the ZTK callipers right?

All depends on the internal geometry but I confirmed direct with Autec that 18" Bavaris fit with big brakes. The ABE/TUV was reassuring too.

[Pentland]

Alloywheelsdirect are good for genuine set ups and you can call for helpful advice.

[felixlamb]

Potentially got a good deal on a set of 4 fronts - OEM Model 630, from the 6 series GT:
https://www.alloywheelsdirect.net/bm...630_wheel_6510

8.5Jx19 ET25 - so the same as the OEM fronts (with ZTK package).

Seems like best option would be 245/35/19 square, to allow for rotation.

Fitment should be good, I think?

Front fitment will be identical.
Rear fitment will be 2.7mm less poke, and 22.7mm further away from the strut.

Seems too good to be true? Am I missing something?

[RockCrusher]

Originally Posted by felixlamb

Hey,

I used to own an E89 Z4. Summers were original rims with 235/35/19 8J front, 265/30/19 9J rear for summers. For winter, I swapped on a square 225/45/19 7.5J and sorted fitment with spacers.

I'm looking to get a decent winter set up for the upcoming UK winter months for my new M240i xDrive. Ideally, I'd prefer a square set up, so that I can rotate from front to rear as appropriate, and likely thinking 18" rims as the tyres will be a little cheaper and will have a bit more sidewall.

Theoretically, I could get a set of 4 front alloys, either model 770 (8J ET20, or 798M (8.5J ET30), and they'd fit about right, with some 245s all around.

Is this an insane thing to do? It doesn't need to look pretty - that's what my 893Ms are for. It just needs to be functional, without looking horriffic or mucking up handling etc. I'm hoping used OEM alloys would be the most price-effective method too.

My advice is check with BMW to see what winter wheel/tire sets it sanctions.

I am concerned about going with a square setup that might change the revs per mile relationship between the front and rear tires and possibly affect the AWD.

[felixlamb]

Originally Posted by RockCrusher

My advice is check with BMW to see what winter wheel/tire sets it sanctions.

I am concerned about going with a square setup that might change the revs per mile relationship between the front and rear tires and possibly affect the AWD.

In theory, 245/35 square is identical to the OEM fronts, and only 1% smaller circumference at the rear (2054.92mm vs 2076.91mm). That should be well within tolerance?

[IanH]

Not trying to insult but there is so much misunderstanding around the tire size and awd.

The "limitation of 1%" that I put in quotes because nobody can actually confirm it, is about the difference between the diameter of the front and back tires.

It is not the difference between the tires you put in and the stock tires.

The best possible setup is to have equal tire diameters. The allowable difference is unknown. If you exceed a certain % it's not like your diff will instantly explode but it could wear or have faults over time. YMMV caveat emptor.

[felixlamb]

At the end of the day, the car has been designed to accept a variety of tyre sizes, ranging from 17" to 20", some staggered, some square. Each setup has small or no deviations in rolling radius.

I can't imagine such a small change would mess up the xDrive. It has to accommodate for so many minor differences already.

[JoeyJoeJo]

Originally Posted by felixlamb

In theory, 245/35 square is identical to the OEM fronts, and only 1% smaller circumference at the rear (2054.92mm vs 2076.91mm). That should be well within tolerance?

I have staggered 19 summer, square 18 winter, both OEM, winters specced and fitted by dealer (which they won't do if not within spec for your model).

Total diameter and rolling radius is pretty close across the three variants but not identical, you'll be fine.

[Mike_H_]

0% > 1%

No revs per mile difference.

[felixlamb]

Bringing this thread back from the dead…

As I have the ZTK brakes, it’s unlikely I’ll get 18” wheels to fit. Therefore been looking at 19” instead.

The Style 630s are popping up at a decent price, and the dimensions are the same as the 893m fronts (19x8.5j ET25).

I contacted BMW UK to verify fitment, but they were utterly useless and just said “the computer doesn’t say they fit”. They didn’t provide any further help than that.

So… can anyone confirm whether they will fit? I’m 80% sure that they would, given that the 893m wheels are 19” too. But, I don’t want to spend money on a non-returnable eBay listing and deal with the faff if they don’t fit.

[JoeyJoeJo]

Can't help on 630s but 790 and 796 18s are fine with big brakes and there are loads of third party with TUV/ABE approvals.

I have 796 and there's plenty space although it doesn't look it from the front.
Tyres usually significantly cheaper on 18s too obviously