437M Winter Tires / General Questions

[Sydd]

Hi all,

I apologize if this is a subject that's been discussed before, but I've been having a heck of a time trying to find the right tires for my '15 M3 sedan with the 437M stock 19 inch wheels.

I don't plan on keeping the car for more than a few years, so I'd rather swap the stock 255/275 PSS tires in the winter for winter tires.

My questions are these:

- Does the winter tire for the rear wheels have to match the load rating that the PSS has? I believe the PSS are 275/35/19 100Y XL and I'm having trouble finding 275/35/19 100 XL winter tires.
- Can you (without causing DSC problems or otherwise) mount 255/35/19 winter tires on the 437M rear wheels? Tire Rack's website is recommending a square setup but both the dealership and my local trusted installer said they wouldn't fit 255 tires on the car if the OEM size is 275.
- Lastly, I can much more easily get a set of Continental DWS06 tires that match exactly the OEM sizes front and rear. I've heard these are the best performing (but still not a true winter) all-season tire for light snow duty. If I live in a city like Pittsburgh that doesn't get many major snow storms and the roads are typically salted, would the DWS06 be sufficient?

Any help would be appreciated.

Thank you.

[wsccsw13]

You can use a square setup; BMW sells a square winter setup for the f8x chassis. As far as DCS, you will be fine. This brought up in another thread and I contacted Bosch who developed the system with BMW and manufacture it. The system will detect the changes in circumference and compensate without any changes in parameters; it adapts.

[instarand]

Originally Posted by Sydd

Hi all,

I apologize if this is a subject that's been discussed before, but I've been having a heck of a time trying to find the right tires for my '15 M3 sedan with the 437M stock 19 inch wheels.

I don't plan on keeping the car for more than a few years, so I'd rather swap the stock 255/275 PSS tires in the winter for winter tires.

My questions are these:

- Does the winter tire for the rear wheels have to match the load rating that the PSS has? I believe the PSS are 275/35/19 100Y XL and I'm having trouble finding 275/35/19 100 XL winter tires.
- Can you (without causing DSC problems or otherwise) mount 255/35/19 winter tires on the 437M rear wheels? Tire Rack's website is recommending a square setup but both the dealership and my local trusted installer said they wouldn't fit 255 tires on the car if the OEM size is 275.
- Lastly, I can much more easily get a set of Continental DWS06 tires that match exactly the OEM sizes front and rear. I've heard these are the best performing (but still not a true winter) all-season tire for light snow duty. If I live in a city like Pittsburgh that doesn't get many major snow storms and the roads are typically salted, would the DWS06 be sufficient?

Any help would be appreciated.

Thank you.

Call tirerack customer sales support. I've had excellent experiences with them. They'll be able to tell you every possible combination of wheel and tire, sizes, etc., and will help compare pros and cons of each setup. They use software that knows your car exactly (dimensions, spacing, clearances, loads, ratings, etc.) Tell them your use case and what you're trying to accomplish and they'll help.

[Sydd]

Thanks for the replies guys.

I thought Tire Rack was right as 255/35/19 tires should fit the 437M 19x10 wheel. I confirmed it with the tire manufacture specs themselves. I wonder why I'm having difficulty finding a tire shop that'd be willing to put them on.

If anyone has any idea about my first question (the load rating), would be much appreciated.

I'll call Tire Rack themselves tomorrow and maybe they can offer more advice over the phone like suggested.

[fertech]

I‘m running Continental winter contact ts 860 s, brand new from Conit, 255 96 V XL front and 275 100 V XLback on M473. Perfect!! All seasons are not good for summer and no good choice for winter either! More than 400 hp and rearwheel 😳 keep the all seasons for city driving on the Smart.

[instarand]

Originally Posted by Sydd

Thanks for the replies guys.

I thought Tire Rack was right as 255/35/19 tires should fit the 437M 19x10 wheel. I confirmed it with the tire manufacture specs themselves. I wonder why I'm having difficulty finding a tire shop that'd be willing to put them on.

If anyone has any idea about my first question (the load rating), would be much appreciated.

I'll call Tire Rack themselves tomorrow and maybe they can offer more advice over the phone like suggested.

Yes tirerack will tell you everything. Literally. And they aren't bound by manufacturer "validated" options. They tell you what works and what doesn't. Load included.

[halfempty]

Please see this document from toyo tires explaining load index.

https://toyotires-1524598101.netdna-...s_20151020.pdf

In general, the load index of the tire refers to amount of weight that the tire will support at a given tire pressure. If you look at the chart on page 29 you can see that changing the tire pressure changes the amount of load the tire can handle.

I did a quick search on Tirerack for winter tires in sizes that will fit the rear 437s. They mostly have a load index of 96-100. It is not necessary to chose a tire with the exact same load rating. In general they're all pretty close and you can easily adjust the tire pressure to compensate. Keep in mind that people run all sorts of different tire pressures without any regard for the changes to the load. This should give you some indication as to the relative leeway engineered into load specs required by the car and tire manufacturers, as well most of us never get close to approaching the maximum carrying capacity of the car. I've not seen this topic discussed too often and it is likely the last thing that any of us look at when buying tires. Tirerack wouldn't offer tires that posed a risk to the vehicle because they didn't support the load.

Regarding the size, the 255 will fit however it will be "stretched" just a little bit. This means that the bead of the tire won't be 90degrees to the bead seat of the wheel and therefore the sidewall will angle in slightly. Some installers may shy away from putting on any stretched tires as there are some risks to stretching tires, though usually it's only dangerous in extreme cases. You can call around and ask or check with the dealer to see if they will do it. The other option is to go with a 265 or stock 275. Tirerack has the LM-32 in both of those sizes. I run these tires and they work great. Put 255s in front and 265s in the rear, 100lbs of sandbag in the trunk and you can pretty much go through anything your front bumper will clear (and then some).

When it comes to all-seasons, they will not work well in any snow more than a dusting and even then not well. All it will take is one unplowed or icy hill and you'll regret it. I've been to Pittsburgh and Have seen some of those hills. I myself would be nervous one those hills and only all-seasons. Any real snow and I would be taking the bus or staying home. Stick with switching to a full winter tire when the cold weather comes.