[TupperBMW]

Hi, I am hoping somebody can help me out here with a novice question.

I've got stock Pirelli all season Run flats, 225/40 on 19 inch rims in all 4 tires, it came with my car (M340i Xdrive)

I am interested in a wider rear tire, perhaps 255, and have spotted these (top of the page):

https://www.tirerack.com/tires/tires...RatingsReviews

My question is, can I just fit these on the current stock rims that I have, or do I need new rear rims? Should I be worried that this will mess up the calipers?

I just want to buy tires, I don't want to have to replace anything else in order to change my set up. Unfortunatly, the parts guy at my BMW dealer didn't know the answer to this. Thanks in advance to anybody who can help!

[RedKloud]

You will need wider rims for the 255s. Mine also came with the 225 square setup. I had to buy 19x8.5 rims to put on the 255s on the rear.
You can maybe try 245s all around on your current rims… there's a thread here on that, if you search for it.

[TupperBMW]

Hmmm, I have the 19 inch wheels. I will double check if the rear is 8.5 inches or not

[RedKloud]

Originally Posted by TupperBMW

Hmmm, I have the 19 inch wheels. I will double check if the rear is 8.5 inches or not

If you have 225 tires then the wheels are definitely 19 x 8.

[TupperBMW]

^ Just got my car serviced and they confirmed 8.5 inch rims

[yangryeddie]

Originally Posted by TupperBMW

^ Just got my car serviced and they confirmed 8.5 inch rims

Wow did not know this, I just assumed all the 225s were 8.0

[RedKloud]

Originally Posted by TupperBMW

^ Just got my car serviced and they confirmed 8.5 inch rims

Interesting

[marco000]

Originally Posted by TupperBMW

^ Just got my car serviced and they confirmed 8.5 inch rims

If you got all season tire, 225/40/R19 tire, it should be paired with 19&8J rims.

So it's either a mistake from BMW factory or a mistake from who did the service.

I tend to believe BMW won't make such mistake unless you got the two rims compared side by side. (or you can just meassure the width)

This is mainly because if you buy a 255 tire, it's not really a good fit on 8J rims, even though you can still possibly install it. Might be fine if you're just doing daily driving on highway. But if you do have the plan
to take the car on track day, it's not good.

[ultrared93]

Take one of the rear wheels off and see what is marked on the inside. My Xdrive also has 225/40x19 AS Pirellis and I have 8" wheels all around. As others have noted and Michelin recommends, 8-1/2" would be a minimum for a 255 tire.

[TupperBMW]

^ Yeah, I don't fully trust the service guys at BMW.

One of these days I"m going to go to a local tire shop and ask them to confirm whether my rear rim is 8" or 8.5"

If it's 8.5" I want a wider rear tire (255) for sure. Otherwise I will stick with 225, as I don't think buying a new 19X8.5 rim for the rear is worth it

[GusL]

Can you just stick a tape measure between the spokes? To get an accurate measurement?

[malibuboats91]

Originally Posted by RedKloud

You will need wider rims for the 255s. Mine also came with the 225 square setup. I had to buy 19x8.5 rims to put on the 255s on the rear.
You can maybe try 245s all around on your current rims… there's a thread here on that, if you search for it.

I'm looking at doing the same thing. Do you notice a big difference going from 225 to 255 in the rear? Do you think it's worth the cost of the 2 8.5" wheels? Part of me wonders if throwing on 4 225/40R19 PS4S would be fine, but I also think it's ridiculous these cars have such narrow tires. 🥴

[RedKloud]

Originally Posted by malibuboats91

I'm looking at doing the same thing. Do you notice a big difference going from 225 to 255 in the rear? Do you think it's worth the cost of the 2 8.5" wheels? Part of me wonders if throwing on 4 225/40R19 PS4S would be fine, but I also think it's ridiculous these cars have such narrow tires. 🥴

TBH you won't feel much of a difference in daily driving... BUT as you said the skinny 225s just don't like right on these cars.